diff --git a/litellm/constants.py b/litellm/constants.py
index 32b47bc6b46..50e090eabaf 100644
--- a/litellm/constants.py
+++ b/litellm/constants.py
@@ -1673,6 +1673,9 @@ OPENAI_FINISH_REASONS: Final = [
 ]
 HUMANLOOP_PROMPT_CACHE_TTL_SECONDS: Final = get_env_int("HUMANLOOP_PROMPT_CACHE_TTL_SECONDS", 60)  # 1 minute
 RESPONSE_FORMAT_TOOL_NAME = "json_tool_call"  # default tool name used when converting response format to tool call
+RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION: Final = (
+    "When you are ready to answer, call this tool with your final answer as its input. Do not reply in plain text."
+)
 
 ########################### Logging Callback Constants ###########################
 AZURE_STORAGE_MSFT_VERSION: Final = "2019-07-07"
diff --git a/litellm/llms/anthropic/chat/handler.py b/litellm/llms/anthropic/chat/handler.py
index 4eae06dbcdf..c273c715ba6 100644
--- a/litellm/llms/anthropic/chat/handler.py
+++ b/litellm/llms/anthropic/chat/handler.py
@@ -734,6 +734,7 @@ class ModelResponseIterator:
         self._split_answer_blocks: tuple[str, ...] = ()
         self._withheld_answer_close: str = ""
         self._streamed_answer_keys: frozenset[str] | None = None
+        self._held_prose: str = ""
 
         # For handling partial JSON chunks from fragmentation
         # See: https://github.com/BerriAI/litellm/issues/17473
@@ -826,8 +827,13 @@ class ModelResponseIterator:
         thinking_blocks: list[ChatCompletionThinkingBlock | ChatCompletionRedactedThinkingBlock] = []
 
         if "text" in content_block["delta"]:
-            text = content_block["delta"]["text"]
-            return text, tool_use, thinking_blocks, provider_specific_fields, reasoning_content
+            return (
+                self._hold_prose(content_block["delta"]["text"]),
+                tool_use,
+                thinking_blocks,
+                provider_specific_fields,
+                reasoning_content,
+            )
         self.content_blocks.append(content_block)
         if "partial_json" in content_block["delta"]:
             # Only emit tool calls if we're in a tool_use or server_tool_use block
@@ -1025,7 +1031,7 @@ class ModelResponseIterator:
                 if self.current_content_block_type in _THINKING_BLOCK_TYPES:
                     self.thinking_block_index += 1
                 if content_block_start["content_block"]["type"] == "text":
-                    text = self._release_answer_close() + content_block_start["content_block"]["text"]
+                    text = self._release_answer_close() + self._hold_prose(content_block_start["content_block"]["text"])
                 elif (
                     content_block_start["content_block"]["type"] == "tool_use"
                     or content_block_start["content_block"]["type"] == "server_tool_use"
@@ -1161,7 +1167,7 @@ class ModelResponseIterator:
             elif type_chunk == "message_delta":
                 finish_reason, usage, container, stop_reason_fields = self._handle_message_delta(chunk)
                 provider_specific_fields.update(stop_reason_fields)
-                text = self._release_answer_close() + self._drain_split_answer_blocks()
+                text = self._release_answer_close() + self._drain_split_answer_blocks() + self._release_held_prose()
                 if container:
                     provider_specific_fields["container"] = container
                     # Store container_id and re-emit code_interpreter_results
@@ -1211,7 +1217,9 @@ class ModelResponseIterator:
                     status_code=500,  # it looks like Anthropic API does not return a status code in the chunk error - default to 500
                 )
 
-            text, tool_use = self._handle_json_mode_chunk(text=text, tool_use=tool_use)
+            text, tool_use = self._handle_json_mode_chunk(
+                text=text + self._settle_held_prose(tool_use), tool_use=tool_use
+            )
             refusal_fields: Final = refusal_params(provider_specific_fields)
 
             returned_chunk: Final = ModelResponseStream(
@@ -1309,6 +1317,24 @@ class ModelResponseIterator:
         self._response_format_verdict = _envelope_verdict(buffered, schema, RESPONSE_FORMAT_TOOL_NAME)
         return self._withhold_answer_close(buffered) if self._response_format_verdict == "pass_through" else ""
 
+    def _hold_prose(self, text: str) -> str:
+        if not self.json_mode or self.response_format_schema is None:
+            return text
+        self._held_prose += text
+        return ""
+
+    def _settle_held_prose(self, tool_use: ChatCompletionToolCallChunk | None) -> str:
+        if tool_use is None or tool_use.get("id") is None or self.current_content_block_type != "tool_use":
+            return ""
+        held: Final = self._held_prose
+        self._held_prose = ""
+        return "" if tool_use.get("function", {}).get("name") == RESPONSE_FORMAT_TOOL_NAME else held
+
+    def _release_held_prose(self) -> str:
+        held: Final = self._held_prose
+        self._held_prose = ""
+        return "" if self.converted_response_format_tool else held
+
     def _withhold_answer_close(self, text: str) -> str:
         pending: Final = self._withheld_answer_close + text
         body: Final = pending.rstrip()
@@ -1362,7 +1388,9 @@ class ModelResponseIterator:
 
     def cut_stream_chunk(self) -> ModelResponseStream | None:
         unsent: Final = self._flush_response_format_buffer() if self._response_format_buffer.getvalue() else ""
-        text: Final = unsent + self._release_answer_close() + self._drain_split_answer_blocks()
+        text: Final = (
+            unsent + self._release_answer_close() + self._drain_split_answer_blocks() + self._release_held_prose()
+        )
         if not text:
             return None
         return ModelResponseStream(
diff --git a/litellm/llms/anthropic/chat/transformation.py b/litellm/llms/anthropic/chat/transformation.py
index 09d16181c3a..4f890ed922f 100644
--- a/litellm/llms/anthropic/chat/transformation.py
+++ b/litellm/llms/anthropic/chat/transformation.py
@@ -26,6 +26,7 @@ from litellm.constants import (
     DEFAULT_REASONING_EFFORT_MINIMAL_THINKING_BUDGET,
     DEFAULT_REASONING_EFFORT_XHIGH_THINKING_BUDGET,
     RESPONSE_FORMAT_TOOL_NAME,
+    RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION,
 )
 from litellm.litellm_core_utils.asyncify import is_event_loop_running
 from litellm.litellm_core_utils.core_helpers import (
@@ -1786,7 +1787,7 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
         json_schema: Mapping[str, object] | None,
         request_params: Mapping[str, object],
     ) -> bool:
-        open_object_takes_forced_json_tool: Final = (
+        open_object_takes_json_tool: Final = (
             json_schema is not None
             and schema_has_open_object(json_schema)
             and not self.is_thinking_requested(request_params)
@@ -1794,7 +1795,7 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
             and not request_params.get("tools")
             and not AnthropicModelInfo.forced_tool_use_unsupported(model)
         )
-        return self.uses_native_structured_output(model) and not open_object_takes_forced_json_tool
+        return self.uses_native_structured_output(model) and not open_object_takes_json_tool
 
     def native_output_format_schema(self, json_schema: Mapping[str, object]) -> Mapping[str, object] | None:
         return self.filter_anthropic_output_schema(dict(self._defs_unpacked(json_schema)))
@@ -1809,7 +1810,7 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
         return AnthropicOutputSchema(type="json_schema", schema=dict(native_schema))
 
     def map_response_format_to_anthropic_tool(
-        self, value: dict | None, optional_params: dict, is_thinking_enabled: bool
+        self, value: dict | None, optional_params: dict, tool_is_forced: bool
     ) -> AnthropicMessagesTool | None:
         ignore_response_format_types: Final = ["text"]
         if value is None or value["type"] in ignore_response_format_types:  # value is a no-op
@@ -1827,6 +1828,7 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
 
         _tool: Final = self._create_json_tool_call_for_response_format(
             json_schema=json_schema,
+            description=None if tool_is_forced else RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION,
         )
 
         return _tool
@@ -1929,7 +1931,12 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
             drop_params=drop_params,
             runs_hosted_mcp=self.runs_hosted_mcp,
         )
-        is_thinking_enabled: Final = self.is_thinking_enabled(non_default_params=request_params)
+        response_format_tool_is_forced: Final = (
+            "response_format" in request_params
+            and AnthropicModelInfo.response_format_tool_can_be_forced(
+                model, self._resolved_provider, REQUEST_PARAMS.validate_python(request_params)
+            )
+        )
 
         # NB: ``map_openai_params`` deliberately does NOT sanitize tool names
         # here. Names are the *original* OpenAI names at this stage, and must
@@ -1989,10 +1996,12 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
                     if _output_format is not None:
                         optional_params["output_format"] = _output_format
                 else:
-                    _tool = self.map_response_format_to_anthropic_tool(value, optional_params, is_thinking_enabled)
+                    _tool = self.map_response_format_to_anthropic_tool(
+                        value, optional_params, response_format_tool_is_forced
+                    )
                     if _tool is None:
                         continue
-                    if not is_thinking_enabled and not AnthropicModelInfo.forced_tool_use_unsupported(model):
+                    if response_format_tool_is_forced:
                         _tool_choice = {
                             "name": RESPONSE_FORMAT_TOOL_NAME,
                             "type": "tool",
@@ -2121,12 +2130,14 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
     def _create_json_tool_call_for_response_format(
         self,
         json_schema: dict | None = None,
+        description: str | None = None,
     ) -> AnthropicMessagesTool:
         """
         Handles creating a tool call for getting responses in JSON format.
 
         Args:
             json_schema (Optional[dict]): The JSON schema the response should be in
+            description (Optional[str]): The tool description, left off the tool when None
 
         Returns:
             AnthropicMessagesTool: The tool call to send to Anthropic API to get responses in JSON format
@@ -2143,11 +2154,11 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
         else:
             _input_schema.update(cast(AnthropicInputSchema, json_schema))
 
-        _tool: Final = AnthropicMessagesTool(
-            name=RESPONSE_FORMAT_TOOL_NAME,
-            input_schema=_input_schema,
+        if description is None:
+            return AnthropicMessagesTool(name=RESPONSE_FORMAT_TOOL_NAME, input_schema=_input_schema)
+        return AnthropicMessagesTool(
+            name=RESPONSE_FORMAT_TOOL_NAME, input_schema=_input_schema, description=description
         )
-        return _tool
 
     def should_strip_billing_metadata(self) -> bool:
         """
diff --git a/litellm/llms/anthropic/common_utils.py b/litellm/llms/anthropic/common_utils.py
index bfd1341711a..bc9bd769d83 100644
--- a/litellm/llms/anthropic/common_utils.py
+++ b/litellm/llms/anthropic/common_utils.py
@@ -1141,6 +1141,34 @@ class AnthropicModelInfo(BaseLLMModelInfo):
         """
         return AnthropicModelInfo._supports_model_capability(model, "thinking_always_on", custom_llm_provider)
 
+    @staticmethod
+    def thinks_by_default(model: str, custom_llm_provider: str) -> bool:
+        return AnthropicModelInfo._is_always_on_thinking_model(
+            model, custom_llm_provider
+        ) or AnthropicModelInfo._supports_model_capability(model, "thinking_on_by_default", custom_llm_provider)
+
+    @staticmethod
+    def will_think(model: str, custom_llm_provider: str, request_params: Mapping[str, object]) -> bool:
+        if AnthropicModelInfo._is_always_on_thinking_model(model, custom_llm_provider):
+            return True
+        match request_params:
+            case {"thinking": True | {"type": "enabled" | "adaptive"}}:
+                return True
+            case {"reasoning_effort": effort} if effort is not None and effort != "none":
+                return True
+            case {"thinking": {"type": "disabled"}} | {"reasoning_effort": "none"}:
+                return False
+            case _:
+                return AnthropicModelInfo.thinks_by_default(model, custom_llm_provider)
+
+    @staticmethod
+    def response_format_tool_can_be_forced(
+        model: str, custom_llm_provider: str, request_params: Mapping[str, object]
+    ) -> bool:
+        return not AnthropicModelInfo.forced_tool_use_unsupported(model) and not AnthropicModelInfo.will_think(
+            model, custom_llm_provider, request_params
+        )
+
     @staticmethod
     def _supports_legacy_thinking(model: str, custom_llm_provider: str) -> bool:
         """Whether ``model`` is an adaptive-thinking model that still accepts legacy
diff --git a/litellm/llms/bedrock/chat/converse_transformation.py b/litellm/llms/bedrock/chat/converse_transformation.py
index 056f34f1bf4..03fbc35a97f 100644
--- a/litellm/llms/bedrock/chat/converse_transformation.py
+++ b/litellm/llms/bedrock/chat/converse_transformation.py
@@ -22,6 +22,7 @@ from litellm.anthropic_beta_headers_manager import filter_and_transform_beta_hea
 from litellm.constants import (
     BEDROCK_MIN_THINKING_BUDGET_TOKENS,
     RESPONSE_FORMAT_TOOL_NAME,
+    RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION,
 )
 from litellm.integrations.anthropic_cache_control_hook import (
     MAX_CACHE_CONTROL_BLOCKS,
@@ -950,19 +951,24 @@ class AmazonConverseConfig(BaseConfig):
     def _supports_native_structured_outputs(
         model: str,
         custom_llm_provider: str | None,
+        will_think: bool,
         thinking_requested: bool,
         model_info: Mapping[str, object] | None,
     ) -> bool:
         """Check if the Bedrock model takes native structured outputs (outputConfig.textFormat) for this request.
 
         ``supports_native_structured_output`` in ``litellm.model_cost`` turns it on for every request, and
-        ``supports_bedrock_native_structured_output`` (the deployment's ``model_info`` first) also when the
-        request asks for thinking, which the json tool path would drop. Without thinking, a model that cannot
-        force the json tool gets it unless that key is false.
+        ``supports_bedrock_native_structured_output`` (the deployment's ``model_info`` first) also when Claude
+        will think, which the json tool path would drop. When the request does not ask for thinking, a model
+        that cannot force the json tool gets it unless that key is false.
         Ref: https://docs.aws.amazon.com/bedrock/latest/userguide/structured-output.html
         """
         return bedrock_chat_uses_native_structured_output(
-            model, thinking_requested, custom_llm_provider or "bedrock_converse", model_info
+            model,
+            will_think=will_think,
+            thinking_requested=thinking_requested,
+            custom_llm_provider=custom_llm_provider or "bedrock_converse",
+            model_info=model_info,
         )
 
     @staticmethod
@@ -1005,11 +1011,13 @@ class AmazonConverseConfig(BaseConfig):
         self,
         model: str,
         json_schema: Mapping[str, object],
+        *,
+        will_think: bool,
         thinking_requested: bool,
         model_info: Mapping[str, object] | None,
     ) -> Mapping[str, object] | None:
         if not self._supports_native_structured_outputs(
-            model, self.custom_llm_provider, thinking_requested, model_info
+            model, self.custom_llm_provider, will_think, thinking_requested, model_info
         ):
             return None
         if BedrockModelInfo.get_base_model(model).startswith("anthropic"):
@@ -1095,7 +1103,6 @@ class AmazonConverseConfig(BaseConfig):
         request_params: Final = tool_params_without_hosted_mcp(
             non_default_params, model=model, route="bedrock", drop_params=drop_params
         )
-        is_thinking_enabled: Final = self.is_thinking_enabled(request_params)
         base_model: Final = BedrockModelInfo.get_base_model(model)
         drop_thinking_param: Final = self._is_deepseek_model(model=model, base_model=base_model)
         drop_reasoning_effort_param: Final = self._model_rejects_reasoning_effort_param(
@@ -1109,7 +1116,6 @@ class AmazonConverseConfig(BaseConfig):
                     model=model,
                     optional_params=optional_params,
                     non_default_params=request_params,
-                    is_thinking_enabled=is_thinking_enabled,
                     model_info=model_info,
                 )
             if param == "max_tokens" or param == "max_completion_tokens":
@@ -1314,7 +1320,6 @@ class AmazonConverseConfig(BaseConfig):
         model: str,
         optional_params: dict,
         non_default_params: dict,
-        is_thinking_enabled: bool,
         model_info: Mapping[str, object] | None = None,
     ) -> dict:
         """
@@ -1339,9 +1344,16 @@ class AmazonConverseConfig(BaseConfig):
         if "type" in value and value["type"] == "text":
             return optional_params
 
-        thinking_requested: Final = self.is_thinking_requested(REQUEST_PARAMS.validate_python(non_default_params))
+        request_params: Final = REQUEST_PARAMS.validate_python(non_default_params)
+        thinking_requested: Final = self.is_thinking_requested(request_params)
         native_schema: Final = (
-            self._native_output_schema(model, json_schema, thinking_requested, model_info)
+            self._native_output_schema(
+                model,
+                json_schema,
+                will_think=AnthropicModelInfo.will_think(model, "bedrock", request_params),
+                thinking_requested=thinking_requested,
+                model_info=model_info,
+            )
             if json_schema is not None
             else None
         )
@@ -1359,17 +1371,24 @@ class AmazonConverseConfig(BaseConfig):
         elif json_schema is not None:
             # Fallback: translate to a synthetic tool call
             # https://docs.anthropic.com/en/docs/build-with-claude/tool-use#json-mode
+            tool_is_forced: Final = litellm.utils.supports_tool_choice(
+                model=model, custom_llm_provider=self.custom_llm_provider
+            ) and AnthropicModelInfo.response_format_tool_can_be_forced(model, "bedrock", request_params)
+            schema_description: Final = description if isinstance(description, str) else None
+            instructs_unforced_tool: Final = not tool_is_forced and BedrockModelInfo.get_base_model(model).startswith(
+                "anthropic"
+            )
             _tool: Final = self._create_json_tool_call_for_response_format(
                 json_schema=json_schema,
-                description=description,
+                description=(
+                    " ".join(filter(None, (RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION, schema_description)))
+                    if instructs_unforced_tool
+                    else schema_description
+                ),
             )
             optional_params = self._add_tools_to_optional_params(optional_params=optional_params, tools=[_tool])
 
-            if (
-                litellm.utils.supports_tool_choice(model=model, custom_llm_provider=self.custom_llm_provider)
-                and not is_thinking_enabled
-                and not AnthropicModelInfo.forced_tool_use_unsupported(model)
-            ):
+            if tool_is_forced:
                 optional_params["tool_choice"] = ToolChoiceValuesBlock(
                     tool=SpecificToolChoiceBlock(name=RESPONSE_FORMAT_TOOL_NAME)
                 )
@@ -1380,8 +1399,8 @@ class AmazonConverseConfig(BaseConfig):
         # returns {} instead of the requested JSON. The model already
         # returns JSON when the prompt asks for it.
 
-        # A request that goes native only because the model can't force the json tool keeps the json tool's faked
-        # stream, so it still needs only bedrock:InvokeModel.
+        # A request that goes native without asking for thinking keeps the json tool's faked stream, so it still
+        # needs only bedrock:InvokeModel, unless the model takes native output on every request.
         streams_natively: Final = native_schema is not None and bedrock_chat_opts_into_native_structured_output(
             model, thinking_requested, self.custom_llm_provider or "bedrock_converse", model_info
         )
@@ -2219,8 +2238,8 @@ class AmazonConverseConfig(BaseConfig):
         }
         if additional_request_params:
             data["additionalModelRequestFields"] = additional_request_params
-            if "thinking" in additional_request_params:
-                data["additionalModelResponseFieldPaths"] = ("/usage/output_tokens_details",)
+        if "thinking" in additional_request_params or AnthropicModelInfo.thinks_by_default(model, "bedrock"):
+            data["additionalModelResponseFieldPaths"] = ("/usage/output_tokens_details",)
         if system_content_blocks:
             data["system"] = system_content_blocks
 
diff --git a/litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude_transformation.py b/litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude_transformation.py
index dc85028440f..62e1bee5217 100644
--- a/litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude_transformation.py
+++ b/litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude_transformation.py
@@ -142,14 +142,19 @@ class AmazonAnthropicClaudeConfig(AmazonInvokeConfig, AnthropicConfig):
         json_schema: Mapping[str, object] | None,
         request_params: Mapping[str, object],
     ) -> bool:
-        return self.chat_uses_native_structured_output(
-            model, self.is_thinking_requested(request_params), self._deployment_model_info
-        ) and (json_schema is None or bedrock_cleaned_output_schema(model, json_schema) is not None)
+        return self.chat_uses_native_structured_output(model, request_params, self._deployment_model_info) and (
+            json_schema is None or bedrock_cleaned_output_schema(model, json_schema) is not None
+        )
 
     def chat_uses_native_structured_output(
-        self, model: str, thinking_requested: bool, model_info: Mapping[str, object] | None
+        self, model: str, request_params: Mapping[str, object], model_info: Mapping[str, object] | None
     ) -> bool:
-        return bedrock_chat_uses_native_structured_output(model, thinking_requested, model_info=model_info)
+        return bedrock_chat_uses_native_structured_output(
+            model,
+            will_think=self.will_think(model, "bedrock", request_params),
+            thinking_requested=self.is_thinking_requested(request_params),
+            model_info=model_info,
+        )
 
     def uses_opt_in_native_output(
         self, model: str, optional_params: Mapping[str, object], litellm_params: Mapping[str, object]
@@ -359,7 +364,7 @@ class AmazonAnthropicClaudeConfig(AmazonInvokeConfig, AnthropicConfig):
             request_body=anthropic_request,
             model_info=model_info,
             chat_uses_native_output=lambda: self.chat_uses_native_structured_output(
-                model, self.is_thinking_requested(_NON_DEFAULT_PARAMS.validate_python(filtered_params)), model_info
+                model, _NON_DEFAULT_PARAMS.validate_python(filtered_params), model_info
             ),
         )
         strip_unsupported_bedrock_invoke_output_config_keys(
diff --git a/litellm/llms/bedrock/chat/mantle/transformation.py b/litellm/llms/bedrock/chat/mantle/transformation.py
index 952ca7a2cd4..7e635a61d4d 100644
--- a/litellm/llms/bedrock/chat/mantle/transformation.py
+++ b/litellm/llms/bedrock/chat/mantle/transformation.py
@@ -55,9 +55,11 @@ class AmazonMantleConfig(AmazonAnthropicClaudeConfig):
         )
 
     def chat_uses_native_structured_output(
-        self, model: str, thinking_requested: bool, model_info: Mapping[str, object] | None
+        self, model: str, request_params: Mapping[str, object], model_info: Mapping[str, object] | None
     ) -> bool:
-        return bedrock_chat_opts_into_native_structured_output(model, thinking_requested, model_info=model_info)
+        return bedrock_chat_opts_into_native_structured_output(
+            model, self.will_think(model, "bedrock", request_params), model_info=model_info
+        )
 
     def _default_max_tokens_models(self, model: str, litellm_params: Mapping[str, object]) -> tuple[str, ...]:
         return (f"bedrock_mantle/{model}", *super()._default_max_tokens_models(model, litellm_params))
diff --git a/litellm/llms/bedrock/common_utils.py b/litellm/llms/bedrock/common_utils.py
index c1b3b5616b8..dfee28a7cc9 100644
--- a/litellm/llms/bedrock/common_utils.py
+++ b/litellm/llms/bedrock/common_utils.py
@@ -356,13 +356,15 @@ def bedrock_chat_opts_into_native_structured_output(
 
 def bedrock_chat_uses_native_structured_output(
     model: str,
+    *,
+    will_think: bool,
     thinking_requested: bool,
     custom_llm_provider: str = "bedrock",
     model_info: Mapping[str, object] | None = None,
 ) -> bool:
-    return bedrock_chat_opts_into_native_structured_output(
-        model, thinking_requested, custom_llm_provider, model_info
-    ) or (not thinking_requested and _bedrock_native_output_replaces_unforceable_tool(model, model_info))
+    return bedrock_chat_opts_into_native_structured_output(model, will_think, custom_llm_provider, model_info) or (
+        not thinking_requested and _bedrock_native_output_replaces_unforceable_tool(model, model_info)
+    )
 
 
 def bedrock_native_output_is_deployment_opt_in(
diff --git a/litellm/llms/databricks/chat/transformation.py b/litellm/llms/databricks/chat/transformation.py
index d943718ed73..859211bd40d 100644
--- a/litellm/llms/databricks/chat/transformation.py
+++ b/litellm/llms/databricks/chat/transformation.py
@@ -31,6 +31,7 @@ from litellm.llms.base_llm.base_model_iterator import BaseModelResponseIterator
 from litellm.llms.base_llm.base_utils import (
     type_to_response_format_param,  # pyright: ignore[reportUnknownVariableType]  # base_utils helper returns an untyped dict
 )
+from litellm.llms.base_llm.chat.transformation import REQUEST_PARAMS
 from litellm.types.llms.anthropic import AllAnthropicToolsValues
 from litellm.types.llms.databricks import (
     AllDatabricksContentValues,
@@ -541,12 +542,12 @@ class DatabricksConfig(DatabricksBase, OpenAILikeChatConfig, AnthropicConfig):
         model: str,
         value: dict | None,
         optional_params: dict,
-        is_thinking_enabled: bool,
+        tool_is_forced: bool,
     ) -> DatabricksTool | None:
         if value is None:
             return None
 
-        tool: Final = self.map_response_format_to_anthropic_tool(value, optional_params, is_thinking_enabled)
+        tool: Final = self.map_response_format_to_anthropic_tool(value, optional_params, tool_is_forced)
 
         databricks_tool: Final = self.convert_anthropic_tool_to_databricks_tool(tool)
         return databricks_tool
@@ -579,7 +580,6 @@ class DatabricksConfig(DatabricksBase, OpenAILikeChatConfig, AnthropicConfig):
             if "claude" in model
             else non_default_params
         )
-        is_thinking_enabled: Final = self.is_thinking_enabled(request_params)
         mapped_params: Final = super().map_openai_params(request_params, optional_params, model, drop_params)
         if "claude" in model:
             AnthropicConfig.translate_legacy_thinking_for_adaptive_model(
@@ -596,17 +596,20 @@ class DatabricksConfig(DatabricksBase, OpenAILikeChatConfig, AnthropicConfig):
             mapped_params.pop("max_completion_tokens", None)
 
         if "response_format" in request_params and "claude" in model:
+            tool_is_forced: Final = AnthropicConfig.response_format_tool_can_be_forced(
+                model, "databricks", REQUEST_PARAMS.validate_python(request_params)
+            )
             _tool: Final = self.map_response_format_to_databricks_tool(
                 model,
                 request_params["response_format"],
                 mapped_params,
-                is_thinking_enabled,
+                tool_is_forced,
             )
 
             if _tool is not None:
                 self._add_tools_to_optional_params(optional_params=optional_params, tools=[_tool])
                 optional_params["json_mode"] = True
-                if not is_thinking_enabled:
+                if tool_is_forced:
                     _tool_choice: Final = ChatCompletionToolChoiceObjectParam(
                         type="function",
                         function=ChatCompletionToolChoiceFunctionParam(name=RESPONSE_FORMAT_TOOL_NAME),
diff --git a/litellm/model_prices_and_context_window_backup.json b/litellm/model_prices_and_context_window_backup.json
index 4d576443b30..a292ce0d14e 100644
--- a/litellm/model_prices_and_context_window_backup.json
+++ b/litellm/model_prices_and_context_window_backup.json
@@ -2125,6 +2125,7 @@
     "anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.25e-06,
         "cache_creation_input_token_cost_above_1hr": 1e-05,
@@ -2213,6 +2214,7 @@
     "global.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.25e-06,
         "cache_creation_input_token_cost_above_1hr": 1e-05,
@@ -2301,6 +2303,7 @@
     "us.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.875e-06,
         "cache_creation_input_token_cost_above_1hr": 1.1e-05,
@@ -2389,6 +2392,7 @@
     "eu.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.875e-06,
         "cache_creation_input_token_cost_above_1hr": 1.1e-05,
@@ -2472,6 +2476,7 @@
     "au.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.875e-06,
         "cache_creation_input_token_cost_above_1hr": 1.1e-05,
@@ -2560,6 +2565,7 @@
     "jp.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.875e-06,
         "cache_creation_input_token_cost_above_1hr": 1.1e-05,
@@ -2958,6 +2964,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3002,6 +3009,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3046,6 +3054,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3090,6 +3099,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3134,6 +3144,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3178,6 +3189,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -4063,6 +4075,7 @@
         "deprecation_source": "https://learn.microsoft.com/en-us/azure/foundry/concepts/model-lifecycle-retirement",
         "supports_mid_conversation_system": true,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "input_cost_per_token": 5e-06,
         "output_cost_per_token": 2.5e-05,
         "litellm_provider": "azure_ai",
@@ -4204,6 +4217,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -16507,6 +16521,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -17042,6 +17057,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -21910,6 +21926,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://www.databricks.com/product/pricing/proprietary-foundation-model-serving",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_function_calling": true,
         "supports_mid_conversation_system": true,
@@ -22068,6 +22085,7 @@
         "prompt_cache_min_tokens": 1024,
         "source": "https://www.databricks.com/product/pricing/proprietary-foundation-model-serving",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_function_calling": true,
         "supports_mid_conversation_system": true,
@@ -50492,6 +50510,7 @@
         "prompt_cache_min_tokens": 1024,
         "source": "https://aws.amazon.com/bedrock/pricing/",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -50569,6 +50588,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrockFoundationModels/current/us-gov-west-1/index.json",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -52974,6 +52994,7 @@
         "regional_endpoint_uplift_multiplier": 1.1,
         "supports_mid_conversation_system": true,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "cache_creation_input_token_cost": 6.25e-06,
         "cache_creation_input_token_cost_above_1hr": 1e-05,
         "cache_creation_input_token_cost_batches": 3.125e-06,
@@ -53012,6 +53033,7 @@
         "regional_endpoint_uplift_multiplier": 1.1,
         "supports_mid_conversation_system": true,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "cache_creation_input_token_cost": 6.25e-06,
         "cache_creation_input_token_cost_above_1hr": 1e-05,
         "cache_creation_input_token_cost_batches": 3.125e-06,
@@ -53261,6 +53283,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -60636,6 +60659,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -64770,6 +64794,14 @@
                     "thinking_always_on": true
                 }
             },
+            {
+                "name": "claude-thinking-on-by-default",
+                "pattern": "claude-[a-z]+-[5-9](?!\\d)",
+                "description": "Claude at major 5 or higher, in any id shape that contains claude-<family>-<major>. Anthropic's thinking docs list every Claude 5+ model as thinking by default (on or always on) when the request sends no thinking param, and every 4.x as off. Two-digit majors are deliberately not matched so ids like claude-opus-41 (4.1) are not read as major 41. The response_format json tool is then left unforced, since a forced tool call skips the model's thinking.",
+                "model_info": {
+                    "thinking_on_by_default": true
+                }
+            },
             {
                 "name": "claude-mid-conversation-system",
                 "pattern": "claude-[a-z]+-(?:4[-._](?:[89]|[1-9]\\d)(?!\\d)|[5-9](?!\\d)(?:[-._]\\d{1,2}(?!\\d))?)",
@@ -69293,6 +69325,7 @@
         "output_cost_per_token": 1.2e-05,
         "prompt_cache_min_tokens": 1024,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -69368,6 +69401,7 @@
         "output_cost_per_token": 3e-05,
         "prompt_cache_min_tokens": 512,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -69624,6 +69658,7 @@
         "output_cost_per_token": 1.2e-05,
         "prompt_cache_min_tokens": 1024,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -69689,6 +69724,7 @@
         "output_cost_per_token": 3e-05,
         "prompt_cache_min_tokens": 512,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -75440,6 +75476,7 @@
     "apac.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "litellm_provider": "bedrock_converse",
         "supports_tool_search": true,
@@ -75556,6 +75593,7 @@
         "max_output_tokens": 128000,
         "mode": "chat",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77060,6 +77098,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77112,6 +77151,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77156,6 +77196,7 @@
         "thinking_always_on": false,
         "prompt_cache_min_tokens": 512,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77203,6 +77244,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77239,6 +77281,7 @@
         "max_output_tokens": 128000,
         "mode": "chat",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77295,6 +77338,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77341,6 +77385,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77381,6 +77426,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrockFoundationModels/current/index.json",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77422,6 +77468,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrockFoundationModels/current/index.json",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77468,6 +77515,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77519,6 +77567,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77565,6 +77614,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77625,6 +77675,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrockFoundationModels/current/index.json",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77676,6 +77727,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77726,6 +77778,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77770,6 +77823,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -79529,6 +79583,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -79743,6 +79798,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -79909,6 +79965,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -81894,6 +81951,7 @@
         "prompt_cache_min_tokens": 512.0,
         "source": "https://www.databricks.com/product/pricing/proprietary-foundation-model-serving",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_anthropic_thinking_payload": true,
         "supports_assistant_prefill": false,
         "supports_function_calling": true,
diff --git a/litellm/types/utils.py b/litellm/types/utils.py
index 4c47489e08f..ba29a67a36c 100644
--- a/litellm/types/utils.py
+++ b/litellm/types/utils.py
@@ -224,6 +224,7 @@ class ProviderSpecificModelInfo(TypedDict, total=False):
     supports_adaptive_thinking: bool | None
     supports_legacy_thinking: ReadOnly[bool | None]
     thinking_always_on: ReadOnly[bool | None]
+    thinking_on_by_default: ReadOnly[bool | None]
     supports_tool_search: bool | None
     supports_mid_conversation_system: bool | None
     supports_url_context: bool | None
diff --git a/litellm/utils.py b/litellm/utils.py
index 4add9d53cb3..7f81ece8314 100644
--- a/litellm/utils.py
+++ b/litellm/utils.py
@@ -7581,6 +7581,7 @@ def get_model_info_helper(
                 supports_adaptive_thinking=_model_info.get("supports_adaptive_thinking", None),
                 supports_legacy_thinking=_model_info.get("supports_legacy_thinking", None),
                 thinking_always_on=_model_info.get("thinking_always_on", None),
+                thinking_on_by_default=_model_info.get("thinking_on_by_default", None),
                 supports_tool_search=_model_info.get("supports_tool_search", None),
                 supports_mid_conversation_system=_model_info.get("supports_mid_conversation_system", None),
                 supports_anthropic_thinking_payload=_model_info.get("supports_anthropic_thinking_payload", None),
diff --git a/model_prices_and_context_window.json b/model_prices_and_context_window.json
index 4d576443b30..a292ce0d14e 100644
--- a/model_prices_and_context_window.json
+++ b/model_prices_and_context_window.json
@@ -2125,6 +2125,7 @@
     "anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.25e-06,
         "cache_creation_input_token_cost_above_1hr": 1e-05,
@@ -2213,6 +2214,7 @@
     "global.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.25e-06,
         "cache_creation_input_token_cost_above_1hr": 1e-05,
@@ -2301,6 +2303,7 @@
     "us.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.875e-06,
         "cache_creation_input_token_cost_above_1hr": 1.1e-05,
@@ -2389,6 +2392,7 @@
     "eu.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.875e-06,
         "cache_creation_input_token_cost_above_1hr": 1.1e-05,
@@ -2472,6 +2476,7 @@
     "au.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.875e-06,
         "cache_creation_input_token_cost_above_1hr": 1.1e-05,
@@ -2560,6 +2565,7 @@
     "jp.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "cache_creation_input_token_cost": 6.875e-06,
         "cache_creation_input_token_cost_above_1hr": 1.1e-05,
@@ -2958,6 +2964,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3002,6 +3009,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3046,6 +3054,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3090,6 +3099,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3134,6 +3144,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -3178,6 +3189,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -4063,6 +4075,7 @@
         "deprecation_source": "https://learn.microsoft.com/en-us/azure/foundry/concepts/model-lifecycle-retirement",
         "supports_mid_conversation_system": true,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "input_cost_per_token": 5e-06,
         "output_cost_per_token": 2.5e-05,
         "litellm_provider": "azure_ai",
@@ -4204,6 +4217,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -16507,6 +16521,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -17042,6 +17057,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -21910,6 +21926,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://www.databricks.com/product/pricing/proprietary-foundation-model-serving",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_function_calling": true,
         "supports_mid_conversation_system": true,
@@ -22068,6 +22085,7 @@
         "prompt_cache_min_tokens": 1024,
         "source": "https://www.databricks.com/product/pricing/proprietary-foundation-model-serving",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_function_calling": true,
         "supports_mid_conversation_system": true,
@@ -50492,6 +50510,7 @@
         "prompt_cache_min_tokens": 1024,
         "source": "https://aws.amazon.com/bedrock/pricing/",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -50569,6 +50588,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrockFoundationModels/current/us-gov-west-1/index.json",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -52974,6 +52994,7 @@
         "regional_endpoint_uplift_multiplier": 1.1,
         "supports_mid_conversation_system": true,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "cache_creation_input_token_cost": 6.25e-06,
         "cache_creation_input_token_cost_above_1hr": 1e-05,
         "cache_creation_input_token_cost_batches": 3.125e-06,
@@ -53012,6 +53033,7 @@
         "regional_endpoint_uplift_multiplier": 1.1,
         "supports_mid_conversation_system": true,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "cache_creation_input_token_cost": 6.25e-06,
         "cache_creation_input_token_cost_above_1hr": 1e-05,
         "cache_creation_input_token_cost_batches": 3.125e-06,
@@ -53261,6 +53283,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -60636,6 +60659,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -64770,6 +64794,14 @@
                     "thinking_always_on": true
                 }
             },
+            {
+                "name": "claude-thinking-on-by-default",
+                "pattern": "claude-[a-z]+-[5-9](?!\\d)",
+                "description": "Claude at major 5 or higher, in any id shape that contains claude-<family>-<major>. Anthropic's thinking docs list every Claude 5+ model as thinking by default (on or always on) when the request sends no thinking param, and every 4.x as off. Two-digit majors are deliberately not matched so ids like claude-opus-41 (4.1) are not read as major 41. The response_format json tool is then left unforced, since a forced tool call skips the model's thinking.",
+                "model_info": {
+                    "thinking_on_by_default": true
+                }
+            },
             {
                 "name": "claude-mid-conversation-system",
                 "pattern": "claude-[a-z]+-(?:4[-._](?:[89]|[1-9]\\d)(?!\\d)|[5-9](?!\\d)(?:[-._]\\d{1,2}(?!\\d))?)",
@@ -69293,6 +69325,7 @@
         "output_cost_per_token": 1.2e-05,
         "prompt_cache_min_tokens": 1024,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -69368,6 +69401,7 @@
         "output_cost_per_token": 3e-05,
         "prompt_cache_min_tokens": 512,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -69624,6 +69658,7 @@
         "output_cost_per_token": 1.2e-05,
         "prompt_cache_min_tokens": 1024,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -69689,6 +69724,7 @@
         "output_cost_per_token": 3e-05,
         "prompt_cache_min_tokens": 512,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -75440,6 +75476,7 @@
     "apac.anthropic.claude-opus-5": {
         "bedrock_converse_supports_strict_tools": false,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "litellm_provider": "bedrock_converse",
         "supports_tool_search": true,
@@ -75556,6 +75593,7 @@
         "max_output_tokens": 128000,
         "mode": "chat",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77060,6 +77098,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77112,6 +77151,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77156,6 +77196,7 @@
         "thinking_always_on": false,
         "prompt_cache_min_tokens": 512,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77203,6 +77244,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77239,6 +77281,7 @@
         "max_output_tokens": 128000,
         "mode": "chat",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77295,6 +77338,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77341,6 +77385,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77381,6 +77426,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrockFoundationModels/current/index.json",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77422,6 +77468,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrockFoundationModels/current/index.json",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77468,6 +77515,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77519,6 +77567,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77565,6 +77614,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77625,6 +77675,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://pricing.us-east-1.amazonaws.com/offers/v1.0/aws/AmazonBedrockFoundationModels/current/index.json",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77676,6 +77727,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -77726,6 +77778,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -77770,6 +77823,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
         "supports_function_calling": true,
@@ -79529,6 +79583,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -79743,6 +79798,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -79909,6 +79965,7 @@
             "search_context_size_medium": 0.01
         },
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_mid_conversation_system": true,
         "supports_assistant_prefill": false,
         "supports_computer_use": true,
@@ -81894,6 +81951,7 @@
         "prompt_cache_min_tokens": 512.0,
         "source": "https://www.databricks.com/product/pricing/proprietary-foundation-model-serving",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_anthropic_thinking_payload": true,
         "supports_assistant_prefill": false,
         "supports_function_calling": true,
diff --git a/tests/integration/providers/test_bedrock_native_structured_output_wire.py b/tests/integration/providers/test_bedrock_native_structured_output_wire.py
index 67edcf7f3e4..2502bd90bd6 100644
--- a/tests/integration/providers/test_bedrock_native_structured_output_wire.py
+++ b/tests/integration/providers/test_bedrock_native_structured_output_wire.py
@@ -622,10 +622,15 @@ def test_messages_thinking_on_a_bedrock_converse_native_model_gets_native_output
 
 
 @pytest.mark.parametrize("route", ["converse", "invoke"])
-def test_bedrock_native_model_without_thinking_keeps_the_forced_json_tool(gateway: Gateway, route: str) -> None:
+@pytest.mark.parametrize(
+    ("backend", "thinks_by_default"), [(_OPUS_4_8, False), (_HAIKU, True)], ids=["opus_4_8", "haiku_5_5"]
+)
+def test_bedrock_native_model_with_no_thinking_param_gets_native_output_only_when_it_thinks_by_default(
+    gateway: Gateway, route: str, backend: str, thinks_by_default: bool
+) -> None:
     marker, marker_hex = _marker()
     with wire_server(_bedrock) as wire, gateway.scenario() as scenario:
-        model: Final = _deployment(scenario, wire, route, _HAIKU)
+        model: Final = _deployment(scenario, wire, route, backend)
         response: Final = gateway.request(
             "POST", "/v1/chat/completions", _chat_body(model, marker, response_format=_response_format(_SCHEMA))
         )
@@ -634,6 +639,9 @@ def test_bedrock_native_model_without_thinking_keeps_the_forced_json_tool(gatewa
         assert not message.get("tool_calls"), response.text
         _, body = _one_call(wire, marker_hex)
         invoke: Final = route == "invoke"
+        if thinks_by_default:
+            _assert_native_without_tools(body, invoke, _SCHEMA)
+            return
         assert _native_schema(body, invoke) is None, body
         assert _tools(body, invoke)[_JSON_TOOL]["properties"] == _SCHEMA["properties"], body
 
diff --git a/tests/integration/providers/test_vertex_anthropic_structured_output_wire.py b/tests/integration/providers/test_vertex_anthropic_structured_output_wire.py
index db81ff70263..19928ecd6e0 100644
--- a/tests/integration/providers/test_vertex_anthropic_structured_output_wire.py
+++ b/tests/integration/providers/test_vertex_anthropic_structured_output_wire.py
@@ -34,14 +34,20 @@ from pydantic import JsonValue, TypeAdapter
 pytestmark: Final = pytest.mark.shares_worker_state
 
 _JSON_TOOL: Final = "json_tool_call"
+_UNFORCED_JSON_TOOL_DESCRIPTION: Final = (
+    "When you are ready to answer, call this tool with your final answer as its input. Do not reply in plain text."
+)
 _USER_TOOL: Final = "lookup"
 _STRUCTURED_OUTPUTS_BETA: Final = "structured-outputs-2025-11-13"
 _TOOL_MODEL: Final = "claude-sonnet-5"
 _EFFORT_GATED_MODEL: Final = "claude-haiku-4-5"
 _NATIVE_MODEL: Final = "claude-opus-5-5"
-_FORCED_TOOL_NATIVE_MODEL: Final = "claude-haiku-5-5"
+_FORCED_TOOL_NATIVE_MODEL: Final = "claude-opus-4-8"
+_THINKING_BY_DEFAULT_NATIVE_MODEL: Final = "claude-haiku-5-5"
+_THINKING_OFF_TOOL_MODEL: Final = "claude-opus-4-8"
 _UNMAPPED_MODEL: Final = "claude-scripted-9"
 _BEDROCK_INVOKE_MODEL: Final = "anthropic.claude-sonnet-5"
+_BEDROCK_TOOL_PATH_MODEL: Final = "anthropic.claude-opus-4-8"
 _BEDROCK_JSON_TOOL_MODEL: Final = "us.anthropic.claude-opus-4-8"
 _THINKING_SIGNATURE: Final = "c2NyaXB0ZWQtc2lnbmF0dXJl"
 _PROJECT: Final = "scripted-project"
@@ -608,11 +614,15 @@ def _one_delivery(wire: Wire, marker_hex: str) -> _Delivery:
     return sent
 
 
-def _json_tool_schema(delivery: _Delivery) -> dict[str, JsonValue]:
+def _json_tool(delivery: _Delivery) -> dict[str, JsonValue]:
     tools: Final = tuple(object_value(tool) for tool in list_value(delivery.body["tools"]))
     (json_tool,) = tuple(tool for tool in tools if tool["name"] == _JSON_TOOL)
-    assert json_tool.keys() == {"name", "input_schema"}, json_tool
-    return object_value(json_tool["input_schema"])
+    assert json_tool.keys() - {"description"} == {"name", "input_schema"}, json_tool
+    return json_tool
+
+
+def _json_tool_schema(delivery: _Delivery) -> dict[str, JsonValue]:
+    return object_value(_json_tool(delivery)["input_schema"])
 
 
 def _folded_format(delivery: _Delivery) -> dict[str, JsonValue]:
@@ -830,10 +840,10 @@ def _family_deployment(gateway: Gateway, scenario: Scenario, api_base: str, memb
         case "azure_ai_unmapped":
             return scenario.model(model=f"azure_ai/{_UNMAPPED_MODEL}", api_base=api_base, api_key=_AZURE_KEY)
         case "bedrock_invoke":
-            return _bedrock_invoke_deployment(scenario, api_base, _BEDROCK_INVOKE_MODEL)
+            return _bedrock_invoke_deployment(scenario, api_base, _BEDROCK_TOOL_PATH_MODEL)
         case "bedrock_mantle":
             return scenario.model(
-                model=f"bedrock_mantle/{_BEDROCK_INVOKE_MODEL}",
+                model=f"bedrock_mantle/{_BEDROCK_TOOL_PATH_MODEL}",
                 api_base=api_base,
                 api_key=_MANTLE_KEY,
                 aws_region_name="us-east-1",
@@ -1448,21 +1458,24 @@ def test_tool_path_stream_cut_before_the_tool_block_closes_still_delivers_the_an
         _one_delivery(wire, marker_hex)
 
 
-@pytest.mark.parametrize("accepts_forced_tools", [True, False], ids=["accepts_forced_tools", "rejects_forced_tools"])
-def test_vertex_chat_json_schema_forces_the_json_tool_only_when_the_model_accepts_forced_tools(
-    gateway: Gateway, accepts_forced_tools: bool
+@pytest.mark.parametrize(
+    ("tool_model", "forced"),
+    [(_THINKING_OFF_TOOL_MODEL, True), (_TOOL_MODEL, False), (None, False)],
+    ids=["accepts_forced_tools", "thinks_by_default", "rejects_forced_tools"],
+)
+def test_vertex_chat_json_schema_forces_the_json_tool_only_when_the_model_will_not_think(
+    gateway: Gateway, tool_model: str | None, forced: bool
 ) -> None:
     marker, marker_hex = _marker("plain")
-    backend: Final = (
-        _TOOL_MODEL if accepts_forced_tools else _claude_rejecting_forced_tools(gateway, "vertex_ai/", "claude")
-    )
+    backend: Final = tool_model or _claude_rejecting_forced_tools(gateway, "vertex_ai/", "claude")
     with wire_server(_peer) as wire, gateway.scenario() as scenario:
         model: Final = _vertex_deployment(gateway, scenario, wire.url, backend)
         response: Final = gateway.request("POST", "/v1/chat/completions", _chat_body(model, marker))
         assert _chat_content(response) == _payload(marker_hex), response.text
         sent: Final = _one_delivery(wire, marker_hex)
         assert _json_tool_schema(sent)["properties"] == _SCHEMA["properties"], sent.body
-        assert sent.body.get("tool_choice") == (_FORCED_JSON_TOOL if accepts_forced_tools else None), sent.body
+        assert sent.body.get("tool_choice") == (_FORCED_JSON_TOOL if forced else None), sent.body
+        assert _json_tool(sent).get("description") == (None if forced else _UNFORCED_JSON_TOOL_DESCRIPTION), sent.body
         assert "output_config" not in sent.body and "output_format" not in sent.body, sent.body
 
 
@@ -1566,6 +1579,25 @@ def test_native_model_json_schema_with_an_open_object_takes_the_json_tool_and_ke
         sent: Final = _one_delivery(wire, marker_hex)
         assert not _structured(sent.body), sent.body
         assert _json_tool_schema(sent)["properties"] == _VALUES_SCHEMA["properties"], sent.body
+        assert sent.body.get("tool_choice") == _FORCED_JSON_TOOL, sent.body
+
+
+@pytest.mark.parametrize("provider", ["anthropic", "azure_ai"])
+def test_open_object_schema_takes_the_unforced_json_tool_on_a_model_that_thinks_by_default(
+    gateway: Gateway, provider: str
+) -> None:
+    marker, marker_hex = _marker("values")
+    with wire_server(_peer) as wire, gateway.scenario() as scenario:
+        model: Final = _native_deployment(gateway, scenario, wire.url, provider, _THINKING_BY_DEFAULT_NATIVE_MODEL)
+        response: Final = gateway.request(
+            "POST", "/v1/chat/completions", _chat_body(model, marker, response_format=_VALUES_RESPONSE_FORMAT)
+        )
+        assert _chat_content(response) == _tool_input("values", marker_hex), response.text
+        sent: Final = _one_delivery(wire, marker_hex)
+        assert not _structured(sent.body), sent.body
+        assert _json_tool_schema(sent)["properties"] == _VALUES_SCHEMA["properties"], sent.body
+        assert _json_tool(sent).get("description") == _UNFORCED_JSON_TOOL_DESCRIPTION, sent.body
+        assert "tool_choice" not in sent.body, sent.body
 
 
 @pytest.mark.parametrize(
diff --git a/tests/integration/routing/test_reasoning_effort_levels_wire.py b/tests/integration/routing/test_reasoning_effort_levels_wire.py
index d15867ac572..efca26d38d0 100644
--- a/tests/integration/routing/test_reasoning_effort_levels_wire.py
+++ b/tests/integration/routing/test_reasoning_effort_levels_wire.py
@@ -1977,6 +1977,9 @@ _INVOKE_NATIVE_OUTPUT: Final[dict[str, JsonValue]] = {
     "format": {"type": "json_schema", "schema": _NATIVE_OUTPUT_SCHEMA},
 }
 _JSON_TOOL: Final = "json_tool_call"
+_UNFORCED_JSON_TOOL_DESCRIPTION: Final = (
+    "When you are ready to answer, call this tool with your final answer as its input. Do not reply in plain text."
+)
 _CONVERSE_TOOL_SCHEMA: Final[dict[str, JsonValue]] = {
     key: value for key, value in _NATIVE_OUTPUT_SCHEMA.items() if key != "additionalProperties"
 }
@@ -1994,7 +1997,7 @@ _CONVERSE_WITH_JSON_TOOL: Final = _with_fields(
                 {
                     "toolSpec": {
                         "name": _JSON_TOOL,
-                        "description": _JSON_TOOL,
+                        "description": _UNFORCED_JSON_TOOL_DESCRIPTION,
                         "inputSchema": {"json": _CONVERSE_TOOL_SCHEMA},
                     }
                 }
@@ -2004,7 +2007,15 @@ _CONVERSE_WITH_JSON_TOOL: Final = _with_fields(
 )
 _INVOKE_WITH_JSON_TOOL: Final = _with_fields(
     _without(_invoke_chat("high", _ADAPTIVE, ()), "anthropic_beta"),
-    {"tools": [{"name": _JSON_TOOL, "input_schema": _NATIVE_OUTPUT_SCHEMA}]},
+    {
+        "tools": [
+            {
+                "name": _JSON_TOOL,
+                "description": _UNFORCED_JSON_TOOL_DESCRIPTION,
+                "input_schema": _NATIVE_OUTPUT_SCHEMA,
+            }
+        ]
+    },
 )
 
 
diff --git a/tests/integration/sdk/test_anthropic_json_tool_cut_stream_sync_sdk.py b/tests/integration/sdk/test_anthropic_json_tool_cut_stream_sync_sdk.py
index 54a6df02edf..294791128ab 100644
--- a/tests/integration/sdk/test_anthropic_json_tool_cut_stream_sync_sdk.py
+++ b/tests/integration/sdk/test_anthropic_json_tool_cut_stream_sync_sdk.py
@@ -27,7 +27,7 @@ _RESPONSE_FORMAT: Final[dict[str, JsonValue]] = {
     "json_schema": {"name": "risk", "schema": _SCHEMA},
 }
 _ANTHROPIC_MODEL: Final = "anthropic/claude-scripted-9"
-_BEDROCK_INVOKE_MODEL: Final = "bedrock/invoke/anthropic.claude-sonnet-5"
+_BEDROCK_INVOKE_MODEL: Final = "bedrock/invoke/anthropic.claude-opus-4-8"
 
 
 def _payload(marker_hex: str) -> dict[str, JsonValue]:
diff --git a/tests/integration/translation/chat_completions/response_format/test_chat_completions_response_format_anthropic.py b/tests/integration/translation/chat_completions/response_format/test_chat_completions_response_format_anthropic.py
index 07e4358ff97..5cb7a7eee8e 100644
--- a/tests/integration/translation/chat_completions/response_format/test_chat_completions_response_format_anthropic.py
+++ b/tests/integration/translation/chat_completions/response_format/test_chat_completions_response_format_anthropic.py
@@ -6,7 +6,7 @@ import pytest
 from integration._support.client import Gateway
 from integration._support.provider import SharedProvider
 from integration.translation.case import TranslationTestCase
-from integration.translation.chat_completions.bases.anthropic import CLAUDE_HAIKU_5_5_TEST_CASE
+from integration.translation.chat_completions.bases.anthropic import CLAUDE_OPUS_4_8_TEST_CASE
 from integration.translation.runner import assert_translation
 
 PLACE_SCHEMA: Final = {
@@ -24,25 +24,25 @@ PLACE_TOOL_USE: Final = {
     "caller": {"type": "direct"},
 }
 
-CLAUDE_HAIKU_5_5_JSON_SCHEMA_TEST_CASE: Final = replace(
-    CLAUDE_HAIKU_5_5_TEST_CASE,
+CLAUDE_OPUS_4_8_JSON_SCHEMA_TEST_CASE: Final = replace(
+    CLAUDE_OPUS_4_8_TEST_CASE,
     scenario="json_schema",
     litellm_request={
-        "model": "anthropic/claude-haiku-5-5",
+        "model": "anthropic/claude-opus-4-8",
         "max_tokens": 128,
         "messages": [{"role": "user", "content": PLACE_PROMPT}],
         "response_format": {"type": "json_schema", "json_schema": {"name": "place", "schema": PLACE_SCHEMA}},
         "cache": {"no-cache": True},
     },
     expected_provider_request={
-        "model": "claude-haiku-5-5",
+        "model": "claude-opus-4-8",
         "messages": [{"role": "user", "content": [{"type": "text", "text": PLACE_PROMPT}]}],
         "max_tokens": 128,
         "tool_choice": {"name": "json_tool_call", "type": "tool"},
         "tools": [{"name": "json_tool_call", "input_schema": PLACE_SCHEMA}],
     },
     mock_provider_response={
-        "model": "claude-haiku-5-5",
+        "model": "claude-opus-4-8",
         "id": "msg_011CgCoP2UR3vcM5ZWmEBd8D",
         "type": "message",
         "role": "assistant",
@@ -68,7 +68,7 @@ CLAUDE_HAIKU_5_5_JSON_SCHEMA_TEST_CASE: Final = replace(
         "id": ANY,
         "created": ANY,
         "object": "chat.completion",
-        "model": "anthropic/claude-haiku-5-5",
+        "model": "anthropic/claude-opus-4-8",
         "choices": [
             {
                 "finish_reason": "stop",
@@ -97,11 +97,11 @@ CLAUDE_HAIKU_5_5_JSON_SCHEMA_TEST_CASE: Final = replace(
     },
 )
 
-CLAUDE_HAIKU_5_5_JSON_SCHEMA_TOOL_NAMED_ENVELOPE_TEST_CASE: Final = replace(
-    CLAUDE_HAIKU_5_5_JSON_SCHEMA_TEST_CASE,
+CLAUDE_OPUS_4_8_JSON_SCHEMA_TOOL_NAMED_ENVELOPE_TEST_CASE: Final = replace(
+    CLAUDE_OPUS_4_8_JSON_SCHEMA_TEST_CASE,
     scenario="json_schema_tool_named_envelope",
     mock_provider_response={
-        **CLAUDE_HAIKU_5_5_JSON_SCHEMA_TEST_CASE.mock_provider_response,
+        **CLAUDE_OPUS_4_8_JSON_SCHEMA_TEST_CASE.mock_provider_response,
         "content": [
             {
                 **PLACE_TOOL_USE,
@@ -114,7 +114,7 @@ CLAUDE_HAIKU_5_5_JSON_SCHEMA_TOOL_NAMED_ENVELOPE_TEST_CASE: Final = replace(
 
 @pytest.mark.parametrize(
     "case",
-    [CLAUDE_HAIKU_5_5_JSON_SCHEMA_TEST_CASE, CLAUDE_HAIKU_5_5_JSON_SCHEMA_TOOL_NAMED_ENVELOPE_TEST_CASE],
+    [CLAUDE_OPUS_4_8_JSON_SCHEMA_TEST_CASE, CLAUDE_OPUS_4_8_JSON_SCHEMA_TOOL_NAMED_ENVELOPE_TEST_CASE],
     ids=lambda case: case.id,
 )
 def test_chat_completions_response_format_anthropic(
diff --git a/tests/integration/translation/chat_completions/streaming/test_chat_completions_streaming_anthropic.py b/tests/integration/translation/chat_completions/streaming/test_chat_completions_streaming_anthropic.py
index fca8de69f00..a41752a96cf 100644
--- a/tests/integration/translation/chat_completions/streaming/test_chat_completions_streaming_anthropic.py
+++ b/tests/integration/translation/chat_completions/streaming/test_chat_completions_streaming_anthropic.py
@@ -6,7 +6,7 @@ from integration._support.client import Gateway
 from integration._support.provider import SharedProvider
 from integration.translation.case import SSEFrame, StreamingTranslationTestCase
 from integration.translation.chat_completions.bases.anthropic import (
-    CLAUDE_HAIKU_5_5_TEST_CASE,
+    CLAUDE_OPUS_4_8_TEST_CASE,
     CLAUDE_SONNET_5_5_TEST_CASE,
 )
 from integration.translation.runner import assert_streaming_translation
@@ -158,27 +158,27 @@ def _place_chunk(delta: dict[str, JsonValue]) -> SSEFrame:
             "id": ANY,
             "object": "chat.completion.chunk",
             "created": ANY,
-            "model": "anthropic/claude-haiku-5-5",
+            "model": "anthropic/claude-opus-4-8",
             "choices": [{"index": 0, "delta": delta}],
         }
     )
 
 
-CLAUDE_HAIKU_5_5_JSON_SCHEMA_CUT_STREAM_TEST_CASE: Final = StreamingTranslationTestCase(
+CLAUDE_OPUS_4_8_JSON_SCHEMA_CUT_STREAM_TEST_CASE: Final = StreamingTranslationTestCase(
     scenario="json_schema_cut_stream",
-    litellm_endpoint=CLAUDE_HAIKU_5_5_TEST_CASE.litellm_endpoint,
+    litellm_endpoint=CLAUDE_OPUS_4_8_TEST_CASE.litellm_endpoint,
     litellm_request={
-        "model": "anthropic/claude-haiku-5-5",
+        "model": "anthropic/claude-opus-4-8",
         "max_tokens": 128,
         "messages": [{"role": "user", "content": PLACE_PROMPT}],
         "response_format": {"type": "json_schema", "json_schema": {"name": "place", "schema": PLACE_SCHEMA}},
         "cache": {"no-cache": True},
         "stream": True,
     },
-    expected_provider_endpoint=CLAUDE_HAIKU_5_5_TEST_CASE.expected_provider_endpoint,
-    expected_provider_headers=CLAUDE_HAIKU_5_5_TEST_CASE.expected_provider_headers,
+    expected_provider_endpoint=CLAUDE_OPUS_4_8_TEST_CASE.expected_provider_endpoint,
+    expected_provider_headers=CLAUDE_OPUS_4_8_TEST_CASE.expected_provider_headers,
     expected_provider_request={
-        "model": "claude-haiku-5-5",
+        "model": "claude-opus-4-8",
         "messages": [{"role": "user", "content": [{"type": "text", "text": PLACE_PROMPT}]}],
         "max_tokens": 128,
         "tool_choice": {"name": "json_tool_call", "type": "tool"},
@@ -191,7 +191,7 @@ CLAUDE_HAIKU_5_5_JSON_SCHEMA_CUT_STREAM_TEST_CASE: Final = StreamingTranslationT
             data={
                 "type": "message_start",
                 "message": {
-                    "model": "claude-haiku-5-5",
+                    "model": "claude-opus-4-8",
                     "id": "msg_011CgCoP5RkexwE6N7PRZEca",
                     "type": "message",
                     "role": "assistant",
@@ -263,7 +263,7 @@ CLAUDE_HAIKU_5_5_JSON_SCHEMA_CUT_STREAM_TEST_CASE: Final = StreamingTranslationT
         "id": ANY,
         "object": "chat.completion",
         "created": ANY,
-        "model": "anthropic/claude-haiku-5-5",
+        "model": "anthropic/claude-opus-4-8",
         "choices": [
             {
                 "index": 0,
@@ -276,7 +276,7 @@ CLAUDE_HAIKU_5_5_JSON_SCHEMA_CUT_STREAM_TEST_CASE: Final = StreamingTranslationT
 
 @pytest.mark.parametrize(
     "case",
-    [CLAUDE_SONNET_5_5_STREAMING_TEST_CASE, CLAUDE_HAIKU_5_5_JSON_SCHEMA_CUT_STREAM_TEST_CASE],
+    [CLAUDE_SONNET_5_5_STREAMING_TEST_CASE, CLAUDE_OPUS_4_8_JSON_SCHEMA_CUT_STREAM_TEST_CASE],
     ids=lambda case: case.id,
 )
 def test_chat_completions_streaming_anthropic(
diff --git a/tests/unit/litellm_core_utils/test_fallback_generalizations.py b/tests/unit/litellm_core_utils/test_fallback_generalizations.py
index 327031cfaf9..d8e56c0ae51 100644
--- a/tests/unit/litellm_core_utils/test_fallback_generalizations.py
+++ b/tests/unit/litellm_core_utils/test_fallback_generalizations.py
@@ -563,6 +563,23 @@ def test_shipped_rules_flag_unmapped_fable_as_always_on_thinking(shipped_cost_ma
     assert other.get("thinking_always_on") is None
 
 
+@pytest.mark.parametrize(
+    ("model", "provider", "on_by_default"),
+    [
+        ("claude-opus-5-9", "anthropic", True),
+        ("claude-newfamily-6", "anthropic", True),
+        ("us.anthropic.claude-sonnet-5-9", "bedrock", True),
+        ("claude-opus-4-9", "anthropic", None),
+    ],
+)
+def test_shipped_rules_flag_unmapped_claude_5_and_later_as_thinking_by_default(
+    shipped_cost_map, model, provider, on_by_default
+):
+    assert model not in litellm.model_cost
+    info = litellm.get_model_info(model, custom_llm_provider=provider)
+    assert info.get("thinking_on_by_default") is on_by_default
+
+
 @pytest.mark.parametrize(
     "model,provider",
     [
diff --git a/tests/unit/llms/anthropic/chat/test_anthropic_chat_handler.py b/tests/unit/llms/anthropic/chat/test_anthropic_chat_handler.py
index 7e2786327dc..e81ee2a4e02 100644
--- a/tests/unit/llms/anthropic/chat/test_anthropic_chat_handler.py
+++ b/tests/unit/llms/anthropic/chat/test_anthropic_chat_handler.py
@@ -3140,6 +3140,118 @@ def test_streamed_json_mode_truncated_output_is_passed_through_untouched():
     assert "".join(contents) == '{"name": "json_tool_call", "parameters": {"tier": 3'
 
 
+def _block_events(
+    index: int, block: dict[str, object], deltas: tuple[dict[str, object], ...]
+) -> tuple[dict[str, object], ...]:
+    return (
+        {"type": "content_block_start", "index": index, "content_block": block},
+        *({"type": "content_block_delta", "index": index, "delta": delta} for delta in deltas),
+        {"type": "content_block_stop", "index": index},
+    )
+
+
+def _message_events(*blocks: tuple[dict[str, object], tuple[dict[str, object], ...]]) -> tuple[dict[str, object], ...]:
+    starts_and_deltas: Final = tuple(
+        chain.from_iterable(_block_events(index, block, deltas) for index, (block, deltas) in enumerate(blocks))
+    )
+    return (
+        {
+            "type": "message_start",
+            "message": {
+                "id": "msg_1",
+                "type": "message",
+                "role": "assistant",
+                "model": "claude-opus-5",
+                "content": [],
+                "stop_reason": None,
+                "stop_sequence": None,
+                "usage": {"input_tokens": 10, "output_tokens": 1},
+            },
+        },
+        *starts_and_deltas,
+        {
+            "type": "message_delta",
+            "delta": {"stop_reason": "tool_use", "stop_sequence": None},
+            "usage": {"output_tokens": 40},
+        },
+    )
+
+
+_THINKING_BLOCK: Final = (
+    {"type": "thinking", "thinking": "", "signature": ""},
+    ({"type": "thinking_delta", "thinking": "7 * 142 = 994"}, {"type": "signature_delta", "signature": "sig"}),
+)
+_PREAMBLE_BLOCK: Final = (
+    {"type": "text", "text": ""},
+    ({"type": "text_delta", "text": "**Working it out:** "}, {"type": "text_delta", "text": "the count is **120**"}),
+)
+
+
+def _json_tool_block(answer: dict[str, object]) -> tuple[dict[str, object], tuple[dict[str, object], ...]]:
+    encoded: Final = json.dumps(answer)
+    return (
+        {"type": "tool_use", "id": "toolu_1", "name": RESPONSE_FORMAT_TOOL_NAME, "input": {}},
+        tuple({"type": "input_json_delta", "partial_json": part} for part in (encoded[:5], encoded[5:])),
+    )
+
+
+def _parse_stream(
+    events: tuple[dict[str, object], ...], schema: dict[str, object] | None = _STREAMED_PERSON_SCHEMA
+) -> tuple[ModelResponseStream, ...]:
+    iterator: Final = ModelResponseIterator(
+        streaming_response=MagicMock(),
+        sync_stream=True,
+        json_mode=True,
+        response_format_schema=None if schema is None else response_format_schema(schema),
+    )
+    return tuple(iterator.chunk_parser(event) for event in events)
+
+
+def _joined_content(chunks: tuple[ModelResponseStream, ...]) -> str:
+    return "".join(chunk.choices[0].delta.content or "" for chunk in chunks)
+
+
+def test_streamed_json_mode_drops_prose_written_before_the_json_tool():
+    chunks: Final = _parse_stream(_message_events(_THINKING_BLOCK, _PREAMBLE_BLOCK, _json_tool_block(_STREAMED_PERSON)))
+
+    assert json.loads(_joined_content(chunks)) == _STREAMED_PERSON
+    assert "".join(getattr(chunk.choices[0].delta, "reasoning_content", None) or "" for chunk in chunks) == (
+        "7 * 142 = 994"
+    )
+    assert all(chunk.choices[0].delta.tool_calls is None for chunk in chunks)
+
+
+def test_streamed_json_mode_returns_prose_when_claude_skips_the_json_tool():
+    chunks: Final = _parse_stream(_message_events(_THINKING_BLOCK, _PREAMBLE_BLOCK))
+
+    assert _joined_content(chunks) == "**Working it out:** the count is **120**"
+
+
+def test_streamed_json_mode_sends_prose_ahead_of_a_caller_tool_call():
+    caller_tool: Final = (
+        {"type": "tool_use", "id": "toolu_2", "name": "get_weather", "input": {}},
+        ({"type": "input_json_delta", "partial_json": '{"city": "Paris"}'},),
+    )
+
+    chunks: Final = _parse_stream(_message_events(_PREAMBLE_BLOCK, caller_tool))
+    tool_chunk_index: Final = next(i for i, chunk in enumerate(chunks) if chunk.choices[0].delta.tool_calls)
+
+    assert _joined_content(chunks[: tool_chunk_index + 1]) == "**Working it out:** the count is **120**"
+    assert chunks[tool_chunk_index].choices[0].delta.tool_calls[0].function.name == "get_weather"
+
+
+def test_streamed_native_output_text_is_not_held_back():
+    answer: Final = json.dumps(_STREAMED_PERSON)
+    text_block: Final = (
+        {"type": "text", "text": ""},
+        tuple({"type": "text_delta", "text": part} for part in (answer[:6], answer[6:])),
+    )
+
+    chunks: Final = _parse_stream(_message_events(text_block), schema=None)
+
+    assert tuple(chunk.choices[0].delta.content for chunk in chunks[2:4]) == (answer[:6], answer[6:])
+
+
 def test_streamed_json_mode_tool_name_envelope_is_unwrapped_when_name_is_a_schema_property():
     envelope = json.dumps({"name": RESPONSE_FORMAT_TOOL_NAME, "parameters": _STREAMED_CONTACT})
 
@@ -3565,7 +3677,7 @@ def test_streamed_json_mode_partial_objects_that_repeat_a_field_keep_the_order_t
     assert "".join(contents) == "".join(blocks)
 
 
-def test_streamed_json_mode_text_after_the_answer_follows_the_whole_answer():
+def test_streamed_json_mode_text_after_the_answer_is_dropped_like_the_non_streamed_reply():
     answer = json.dumps(_STREAMED_RISK_OBJECT)
     message_start, *_, message_delta = _json_tool_events(())
     text_block = (
@@ -3576,7 +3688,7 @@ def test_streamed_json_mode_text_after_the_answer_follows_the_whole_answer():
 
     chunks = _json_mode_stream_chunks((message_start, *_json_tool_block_events(0, answer), *text_block, message_delta))
 
-    assert "".join(chunk.choices[0].delta.content or "" for chunk in chunks) == answer + " Done."
+    assert "".join(chunk.choices[0].delta.content or "" for chunk in chunks) == answer
 
 
 def test_streamed_json_mode_envelope_whose_label_is_a_property_name_is_still_unwrapped():
diff --git a/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py b/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
index f1c38ef4e64..80845b1f12d 100644
--- a/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
+++ b/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
@@ -22,6 +22,7 @@ from litellm.constants import (
     DEFAULT_REASONING_EFFORT_MEDIUM_THINKING_BUDGET,
     DEFAULT_REASONING_EFFORT_XHIGH_THINKING_BUDGET,
     RESPONSE_FORMAT_TOOL_NAME,
+    RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION,
 )
 from litellm.litellm_core_utils.prompt_templates.common_utils import encrypted_reasoning_signature
 from litellm.litellm_core_utils.prompt_templates.factory import anthropic_messages_pt
@@ -1424,6 +1425,33 @@ def test_dict_fields_keep_native_output_when_the_json_tool_would_not_be_forced(m
     assert "json_tool_call" not in [tool["name"] for tool in optional_params.get("tools", [])]
 
 
+def test_dict_fields_take_the_unforced_json_tool_on_a_default_thinking_model(local_model_cost_map):
+    optional_params: Final = AnthropicConfig().map_openai_params(
+        non_default_params={
+            "response_format": {
+                "type": "json_schema",
+                "json_schema": {
+                    "name": "out",
+                    "schema": {
+                        "type": "object",
+                        "properties": {"field": {"type": "object", "additionalProperties": {"type": "integer"}}},
+                        "required": ["field"],
+                    },
+                },
+            }
+        },
+        optional_params={},
+        model="claude-opus-5",
+        drop_params=False,
+    )
+
+    assert "output_format" not in optional_params
+    assert "tool_choice" not in optional_params
+    assert [
+        (tool["name"], tool["input_schema"]["properties"]["field"]) for tool in optional_params["tools"]
+    ] == [("json_tool_call", {"type": "object", "additionalProperties": {"type": "integer"}})]
+
+
 def test_native_structured_output_uses_bundled_capability_when_remote_map_lags(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
@@ -6956,6 +6984,63 @@ def test_response_format_tool_path_skips_forced_tool_choice_when_unsupported(loc
     assert "tool_choice" not in result
 
 
+@pytest.mark.parametrize(
+    ("model", "thinking_params", "forced"),
+    [
+        ("claude-opus-4-8", {"thinking": {"type": "adaptive"}}, False),
+        ("claude-opus-5", {}, False),
+        ("claude-sonnet-5", {}, False),
+        ("claude-haiku-5-5", {}, False),
+        ("claude-fable-5", {"reasoning_effort": "none"}, False),
+        ("claude-opus-4-8", {}, True),
+        ("claude-opus-5", {"thinking": {"type": "disabled"}}, True),
+        ("claude-haiku-5-5", {"reasoning_effort": "none"}, True),
+    ],
+    ids=[
+        "opus-4-8-adaptive",
+        "opus-5-default-thinking",
+        "sonnet-5-default-thinking",
+        "haiku-5-5-default-thinking",
+        "fable-5-always-on-reasoning-effort-none",
+        "opus-4-8-default-off",
+        "opus-5-thinking-disabled",
+        "haiku-5-5-reasoning-effort-none",
+    ],
+)
+def test_response_format_tool_is_forced_only_when_the_model_will_not_think(
+    set_native_structured_output, model, thinking_params, forced
+):
+    set_native_structured_output(model, None)
+    config: Final = AnthropicConfig()
+    optional_params: Final = config.map_openai_params(
+        non_default_params={
+            **thinking_params,
+            "response_format": {
+                "type": "json_schema",
+                "json_schema": {
+                    "name": "capital",
+                    "schema": {"type": "object", "properties": {"city": {"type": "string"}}, "required": ["city"]},
+                },
+            },
+        },
+        optional_params={},
+        model=model,
+        drop_params=False,
+    )
+
+    request: Final = config.transform_request(
+        model=model,
+        messages=[{"role": "user", "content": "Name the capital of France."}],
+        optional_params=optional_params,
+        litellm_params={},
+        headers={},
+    )
+
+    assert [tool["name"] for tool in request["tools"]] == ["json_tool_call"]
+    assert (request.get("tool_choice") == {"name": "json_tool_call", "type": "tool"}) is forced
+    assert request["tools"][0].get("description") == (None if forced else RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION)
+
+
 def _eager_chat_function(**extra: object) -> dict[str, object]:
     return {
         "name": "write_file",
diff --git a/tests/unit/llms/bedrock/chat/invoke_transformations/test_bedrock_chat_invoke_transformations_anthropic_claude_transformation.py b/tests/unit/llms/bedrock/chat/invoke_transformations/test_bedrock_chat_invoke_transformations_anthropic_claude_transformation.py
index 34a4cf5225b..93f6e237fc7 100644
--- a/tests/unit/llms/bedrock/chat/invoke_transformations/test_bedrock_chat_invoke_transformations_anthropic_claude_transformation.py
+++ b/tests/unit/llms/bedrock/chat/invoke_transformations/test_bedrock_chat_invoke_transformations_anthropic_claude_transformation.py
@@ -562,19 +562,27 @@ def _invoke_params_for_schema(
 
 
 @pytest.mark.parametrize(
-    ("native_key", "thinking_params", "native"),
+    ("model", "native_key", "thinking_params", "native"),
     [
-        ("legacy", {}, True),
-        ("bedrock", {}, False),
-        ("bedrock", {"thinking": {"type": "adaptive"}}, True),
-        ("bedrock", {"reasoning_effort": "low"}, True),
+        ("us.anthropic.claude-haiku-5-5", "legacy", {}, True),
+        ("us.anthropic.claude-haiku-5-5", "bedrock", {}, True),
+        ("us.anthropic.claude-opus-4-8", "bedrock", {}, False),
+        ("us.anthropic.claude-opus-4-8", "bedrock", {"thinking": {"type": "adaptive"}}, True),
+        ("us.anthropic.claude-opus-4-8", "bedrock", {"reasoning_effort": "low"}, True),
+        ("us.anthropic.claude-haiku-5-5", "bedrock", {"thinking": {"type": "disabled"}}, False),
+    ],
+    ids=[
+        "legacy-key",
+        "bedrock-key-thinking-by-default",
+        "bedrock-key-thinking-off-by-default",
+        "bedrock-key-adaptive",
+        "bedrock-key-effort",
+        "bedrock-key-thinking-disabled",
     ],
-    ids=["legacy-key", "bedrock-key-no-thinking", "bedrock-key-adaptive", "bedrock-key-effort"],
 )
-def test_bedrock_native_output_key_applies_only_when_thinking_is_requested(
-    set_native_structured_output, native_key, thinking_params, native
+def test_bedrock_native_output_key_applies_only_when_the_model_will_think(
+    set_native_structured_output, model, native_key, thinking_params, native
 ):
-    model = "us.anthropic.claude-haiku-5-5"
     set_native_structured_output(model, native_key)
     schema = {"type": "object", "properties": {"answer": {"type": "string"}}, "required": ["answer"]}
 
@@ -914,9 +922,7 @@ def test_bedrock_chat_invoke_tool_based_response_format_still_upgrades_legacy_th
     assert result["output_config"] == {"effort": "high"}
 
 
-def test_bedrock_chat_invoke_adaptive_thinking_keeps_the_forced_response_format_tool(set_native_structured_output):
-    """Anthropic accepts a forced tool_choice next to adaptive thinking, and dropping
-    it lets the model answer in prose instead of the requested JSON."""
+def test_bedrock_chat_invoke_adaptive_thinking_leaves_the_response_format_tool_unforced(set_native_structured_output):
     set_native_structured_output("us.anthropic.claude-opus-5", None)
     result = AmazonAnthropicClaudeConfig().map_openai_params(
         non_default_params={
@@ -935,7 +941,8 @@ def test_bedrock_chat_invoke_adaptive_thinking_keeps_the_forced_response_format_
         drop_params=False,
     )
 
-    assert result["tool_choice"] == {"type": "tool", "name": result["tools"][0]["name"]}
+    assert [tool["name"] for tool in result["tools"]] == ["json_tool_call"]
+    assert "tool_choice" not in result
     assert result["thinking"] == {"type": "adaptive"}
 
 
@@ -2084,7 +2091,7 @@ def test_invoke_uses_opt_in_native_output_is_false_when_native_output_did_not_co
         (False, True, None, {"thinking": {"type": "adaptive"}}, True),
         (False, False, None, {}, False),
         (False, None, {"supports_bedrock_native_structured_output": False}, {}, False),
-        (True, True, None, {}, False),
+        (True, True, None, {"thinking": {"type": "disabled"}}, False),
     ],
     ids=[
         "cannot-force-tool",
diff --git a/tests/unit/llms/bedrock/chat/test_converse_transformation.py b/tests/unit/llms/bedrock/chat/test_converse_transformation.py
index 7c19ef5b751..b8eb5858fda 100644
--- a/tests/unit/llms/bedrock/chat/test_converse_transformation.py
+++ b/tests/unit/llms/bedrock/chat/test_converse_transformation.py
@@ -15,6 +15,7 @@ import respx
 import litellm
 from litellm._logging import verbose_logger
 from litellm import ModelResponse, Router, completion
+from litellm.constants import RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION
 from litellm.litellm_core_utils.prompt_templates.factory import (
     _bedrock_converse_messages_pt,
     _bedrock_tools_pt,
@@ -1440,18 +1441,27 @@ def test_thinking_request_adds_output_tokens_details_response_path():
     assert result["additionalModelResponseFieldPaths"] == ("/usage/output_tokens_details",)
 
 
-def test_request_without_thinking_omits_response_field_paths():
-    config = AmazonConverseConfig()
-
-    result = config._transform_request(
-        model="bedrock/converse/us.anthropic.claude-opus-4-7",
+@pytest.mark.parametrize(
+    ("model", "thinks_by_default"),
+    [
+        ("bedrock/converse/us.anthropic.claude-opus-4-7", False),
+        ("bedrock/converse/us.anthropic.claude-opus-5", True),
+        ("us.anthropic.claude-haiku-5-5", True),
+    ],
+    ids=["opus-4-7-thinking-off-by-default", "opus-5-thinking-on-by-default", "haiku-5-5-thinking-on-by-default"],
+)
+def test_request_without_thinking_asks_for_thinking_tokens_only_when_the_model_thinks_by_default(
+    local_model_cost_map: None, model: str, thinks_by_default: bool
+):
+    result = AmazonConverseConfig()._transform_request(
+        model=model,
         messages=[{"role": "user", "content": "hi"}],
         optional_params={"maxTokens": 256},
         litellm_params={},
         headers={},
     )
 
-    assert "additionalModelResponseFieldPaths" not in result
+    assert (result.get("additionalModelResponseFieldPaths") == ("/usage/output_tokens_details",)) is thinks_by_default
 
 
 def test_transform_usage_prefers_provider_reasoning_tokens():
@@ -4937,7 +4947,6 @@ def test_translate_response_format_native_output_config(monkeypatch):
             model="anthropic.claude-sonnet-4-5-20250929-v1:0",
             optional_params=optional_params,
             non_default_params={"response_format": response_format},
-            is_thinking_enabled=False,
         )
 
         # Should have outputConfig, NOT tools
@@ -4965,20 +4974,20 @@ def test_translate_response_format_native_output_config(monkeypatch):
             monkeypatch.setenv("LITELLM_LOCAL_MODEL_COST_MAP", old_env)
 
 
-CAPITAL_RESPONSE_FORMAT: Final = {
-    "type": "json_schema",
-    "json_schema": {
-        "name": "capital",
-        "schema": {
-            "type": "object",
-            "properties": {"city": {"type": "string"}, "country": {"type": "string"}},
-            "required": ["city", "country"],
-            "additionalProperties": False,
-        },
+CAPITAL_JSON_SCHEMA: Final = {
+    "name": "capital",
+    "schema": {
+        "type": "object",
+        "properties": {"city": {"type": "string"}, "country": {"type": "string"}},
+        "required": ["city", "country"],
+        "additionalProperties": False,
     },
 }
 
 
+CAPITAL_RESPONSE_FORMAT: Final = {"type": "json_schema", "json_schema": CAPITAL_JSON_SCHEMA}
+
+
 ADAPTIVE_THINKING: Final = {"type": "adaptive"}
 
 
@@ -5030,24 +5039,124 @@ def test_json_schema_shape_follows_each_inference_profile_own_native_output_flag
     assert "fake_stream" not in native_params
     assert "outputConfig" not in tool_request
     assert [tool["toolSpec"]["name"] for tool in tool_request["toolConfig"]["tools"]] == ["json_tool_call"]
-    assert tool_request["toolConfig"]["toolChoice"] == {"tool": {"name": "json_tool_call"}}
+    assert "toolChoice" not in tool_request["toolConfig"]
     assert tool_params.get("fake_stream", False) is stream
 
 
+_JSON_TOOL_CHOICE: Final = {"tool": {"name": "json_tool_call"}}
+
+
 @pytest.mark.parametrize(
-    ("native_key", "thinking_params", "native"),
+    ("model", "native_key", "model_info", "thinking_params", "forced"),
     [
-        ("legacy", {}, True),
-        ("bedrock", {}, False),
-        ("bedrock", {"thinking": ADAPTIVE_THINKING}, True),
-        ("bedrock", {"thinking": {"type": "enabled", "budget_tokens": 1024}}, True),
-        ("bedrock", {"reasoning_effort": "low"}, True),
-        ("bedrock", {"reasoning_effort": "none"}, False),
-        ("bedrock", {"thinking": {"type": "disabled"}}, False),
+        (
+            "us.anthropic.claude-opus-4-8",
+            "bedrock",
+            {"supports_bedrock_native_structured_output": False},
+            {"thinking": ADAPTIVE_THINKING},
+            False,
+        ),
+        ("us.anthropic.claude-opus-5", None, None, {}, False),
+        ("global.anthropic.claude-sonnet-5", None, None, {}, False),
+        ("us.anthropic.claude-haiku-5-5", None, None, {}, False),
+        ("us.anthropic.claude-fable-5", None, None, {}, False),
+        ("us.anthropic.claude-fable-5", None, None, {"reasoning_effort": "none"}, False),
+        ("us.anthropic.claude-opus-4-8", None, None, {}, True),
+        ("us.anthropic.claude-opus-5", None, None, {"thinking": {"type": "disabled"}}, True),
+        ("us.anthropic.claude-haiku-5-5", None, None, {"reasoning_effort": "none"}, True),
+    ],
+    ids=[
+        "opus-4-8-adaptive-native-output-fallback",
+        "opus-5-default-thinking",
+        "sonnet-5-default-thinking",
+        "haiku-5-5-default-thinking",
+        "fable-5-always-on",
+        "fable-5-always-on-reasoning-effort-none",
+        "opus-4-8-default-off",
+        "opus-5-thinking-disabled",
+        "haiku-5-5-reasoning-effort-none",
+    ],
+)
+def test_json_tool_is_forced_only_when_the_model_will_not_think(
+    set_native_structured_output, model, native_key, model_info, thinking_params, forced
+):
+    set_native_structured_output(model, native_key)
+    config: Final = AmazonConverseConfig()
+
+    response_format: Final = {
+        "type": "json_schema",
+        "json_schema": {**CAPITAL_JSON_SCHEMA, "description": "The capital of a country"},
+    }
+
+    optional_params: Final = config.map_openai_params(
+        non_default_params={"response_format": response_format, **thinking_params},
+        optional_params={},
+        model=model,
+        drop_params=False,
+        model_info=model_info,
+    )
+    request: Final = config._transform_request(
+        model=model,
+        messages=[{"role": "user", "content": "Name the capital of France."}],
+        optional_params=optional_params,
+        litellm_params={},
+        headers={},
+    )
+
+    assert "outputConfig" not in request
+    assert [tool["toolSpec"]["name"] for tool in request["toolConfig"]["tools"]] == ["json_tool_call"]
+    assert (request["toolConfig"].get("toolChoice") == _JSON_TOOL_CHOICE) is forced
+    assert request["toolConfig"]["tools"][0]["toolSpec"]["description"] == (
+        "The capital of a country"
+        if forced
+        else f"{RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION} The capital of a country"
+    )
+
+
+def test_unforced_json_tool_keeps_the_schema_description_on_a_non_claude_model(set_native_structured_output):
+    model: Final = "us.meta.llama3-3-70b-instruct-v1:0"
+    set_native_structured_output(model, None)
+    config: Final = AmazonConverseConfig()
+
+    optional_params: Final = config.map_openai_params(
+        non_default_params={
+            "response_format": {
+                "type": "json_schema",
+                "json_schema": {**CAPITAL_JSON_SCHEMA, "description": "The capital of a country"},
+            }
+        },
+        optional_params={},
+        model=model,
+        drop_params=False,
+    )
+    request: Final = config._transform_request(
+        model=model,
+        messages=[{"role": "user", "content": "Name the capital of France."}],
+        optional_params=optional_params,
+        litellm_params={},
+        headers={},
+    )
+
+    assert "toolChoice" not in request["toolConfig"]
+    assert [tool["toolSpec"]["description"] for tool in request["toolConfig"]["tools"]] == ["The capital of a country"]
+
+
+@pytest.mark.parametrize(
+    ("model", "native_key", "thinking_params", "native"),
+    [
+        ("us.anthropic.claude-haiku-5-5", "legacy", {}, True),
+        ("us.anthropic.claude-haiku-5-5", "bedrock", {}, True),
+        ("us.anthropic.claude-opus-4-8", "bedrock", {}, False),
+        ("us.anthropic.claude-opus-4-8", "bedrock", {"thinking": ADAPTIVE_THINKING}, True),
+        ("us.anthropic.claude-haiku-5-5", "bedrock", {"thinking": {"type": "enabled", "budget_tokens": 1024}}, True),
+        ("us.anthropic.claude-opus-4-8", "bedrock", {"reasoning_effort": "low"}, True),
+        ("us.anthropic.claude-haiku-5-5", "bedrock", {"reasoning_effort": "none"}, False),
+        ("us.anthropic.claude-haiku-5-5", "bedrock", {"thinking": {"type": "disabled"}}, False),
     ],
     ids=[
         "legacy-key",
-        "bedrock-key-no-thinking",
+        "bedrock-key-thinking-by-default",
+        "bedrock-key-thinking-off-by-default",
         "bedrock-key-adaptive",
         "bedrock-key-enabled",
         "bedrock-key-effort",
@@ -5055,10 +5164,9 @@ def test_json_schema_shape_follows_each_inference_profile_own_native_output_flag
         "bedrock-key-thinking-disabled",
     ],
 )
-def test_bedrock_native_output_key_applies_only_when_thinking_is_requested(
-    set_native_structured_output, native_key, thinking_params, native
+def test_bedrock_native_output_key_applies_only_when_the_model_will_think(
+    set_native_structured_output, model, native_key, thinking_params, native
 ):
-    model: Final = "us.anthropic.claude-haiku-5-5"
     set_native_structured_output(model, native_key)
 
     _, request = _converse_request_for_json_schema(model, False, thinking_params)
@@ -5078,7 +5186,7 @@ _FORCED_JSON_TOOL_CHOICE: Final = {"tool": {"name": "json_tool_call"}}
         (False, True, None, {"thinking": {"type": "adaptive"}}, True, None),
         (False, False, None, None, False, None),
         (False, None, {"supports_bedrock_native_structured_output": False}, None, False, None),
-        (True, True, None, None, False, _FORCED_JSON_TOOL_CHOICE),
+        (True, True, None, {"thinking": {"type": "disabled"}}, False, _FORCED_JSON_TOOL_CHOICE),
     ],
     ids=[
         "cannot-force-tool",
@@ -5596,7 +5704,6 @@ def test_translate_response_format_fallback_tool_call():
         model="anthropic.claude-3-haiku-20240307-v1:0",
         optional_params=optional_params,
         non_default_params={"response_format": response_format},
-        is_thinking_enabled=False,
     )
 
     # Should use tool-call approach, NOT outputConfig (model doesn't support native structured outputs)
@@ -5633,7 +5740,6 @@ def test_native_structured_output_no_fake_stream(monkeypatch):
             model="anthropic.claude-sonnet-4-5-20250929-v1:0",
             optional_params=optional_params,
             non_default_params={"response_format": response_format, "stream": True},
-            is_thinking_enabled=False,
         )
 
         assert "outputConfig" in result
@@ -5954,7 +6060,6 @@ def test_json_object_no_schema_skips_tool_injection(monkeypatch):
             model="anthropic.claude-sonnet-4-5-20250929-v1:0",
             optional_params=optional_params,
             non_default_params=non_default_params,
-            is_thinking_enabled=False,
         )
 
         # Should NOT use native outputConfig (no schema provided)
diff --git a/tests/unit/llms/bedrock/chat/test_invoke_handler.py b/tests/unit/llms/bedrock/chat/test_invoke_handler.py
index 996cfec6e22..4424f7640a3 100644
--- a/tests/unit/llms/bedrock/chat/test_invoke_handler.py
+++ b/tests/unit/llms/bedrock/chat/test_invoke_handler.py
@@ -1149,6 +1149,108 @@ async def test_converse_streaming_completion_yields_text_and_finish_reason(
         _assert_converse_stream_text_and_finish_reason(sync_chunks)
 
 
+_CONVERSE_PROSE: Final = "Let me work this out. "
+
+
+async def _stream_chunks(
+    request: Mapping[str, object], transport: httpx.MockTransport, async_mode: bool
+) -> tuple[ModelResponseStream, ...]:
+    if not async_mode:
+        return tuple(litellm.completion(**request, client=HTTPHandler(client=httpx.Client(transport=transport))))
+    async_stream: Final = await litellm.acompletion(**request, client=AsyncHTTPHandler(transport=transport))
+    return tuple([chunk async for chunk in async_stream])
+
+
+@pytest.mark.parametrize("async_mode", [False, True])
+@pytest.mark.parametrize(
+    ("tool_block", "stop_reason", "expected_content", "expected_tools", "expected_finish_reason"),
+    [
+        pytest.param(
+            {"toolUse": {"toolUseId": "tooluse_1", "name": "json_tool_call", "input": {"answer": 120}}},
+            "tool_use",
+            '{"answer": 120}',
+            (),
+            "stop",
+            id="prose_then_json_tool",
+        ),
+        pytest.param(
+            {"toolUse": {"toolUseId": "tooluse_1", "name": "get_weather", "input": {"city": "Paris"}}},
+            "tool_use",
+            _CONVERSE_PROSE,
+            (("get_weather", '{"city": "Paris"}'),),
+            "tool_calls",
+            id="prose_then_caller_tool",
+        ),
+        pytest.param(None, "end_turn", _CONVERSE_PROSE, (), "stop", id="json_tool_skipped"),
+    ],
+)
+@pytest.mark.asyncio
+async def test_converse_json_schema_stream_sends_claude_prose_only_when_claude_skips_the_json_tool(
+    _aws_test_credentials: None,
+    async_mode: bool,
+    tool_block: Mapping[str, object] | None,
+    stop_reason: str,
+    expected_content: str,
+    expected_tools: tuple[tuple[str, str], ...],
+    expected_finish_reason: str,
+) -> None:
+    converse_reply: Final = {
+        "output": {
+            "message": {
+                "role": "assistant",
+                "content": [{"text": _CONVERSE_PROSE}, *((tool_block,) if tool_block is not None else ())],
+            }
+        },
+        "stopReason": stop_reason,
+        "usage": {"inputTokens": 30, "outputTokens": 20, "totalTokens": 50},
+        "metrics": {"latencyMs": 1},
+    }
+
+    def handle_request(request: httpx.Request) -> httpx.Response:
+        body: Final = json.loads(request.content)
+        assert "toolChoice" not in body["toolConfig"]
+        assert "json_tool_call" in [tool["toolSpec"]["name"] for tool in body["toolConfig"]["tools"]]
+        return httpx.Response(200, json=converse_reply)
+
+    transport: Final = httpx.MockTransport(handle_request)
+    request: Final = {
+        "model": "bedrock/us.anthropic.claude-opus-5",
+        "messages": [{"role": "user", "content": "What is the LCM of 24 and 120? Reply in JSON."}],
+        "response_format": {
+            "type": "json_schema",
+            "json_schema": {
+                "name": "answer",
+                "schema": {"type": "object", "properties": {"answer": {"type": "integer"}}, "required": ["answer"]},
+            },
+        },
+        "tools": [
+            {
+                "type": "function",
+                "function": {
+                    "name": "get_weather",
+                    "parameters": {"type": "object", "properties": {"city": {"type": "string"}}},
+                },
+            }
+        ],
+        "stream": True,
+    }
+    chunks: Final = await _stream_chunks(request, transport, async_mode)
+
+    assert "".join(chunk.choices[0].delta.content or "" for chunk in chunks) == expected_content
+    tool_calls: Final = tuple(
+        itertools.chain.from_iterable(chunk.choices[0].delta.tool_calls or () for chunk in chunks)
+    )
+    named_calls: Final = tuple(
+        (call.function.name, "".join(c.function.arguments or "" for c in tool_calls))
+        for call in tool_calls
+        if call.function.name
+    )
+    assert named_calls == expected_tools
+    assert [chunk.choices[0].finish_reason for chunk in chunks if chunk.choices[0].finish_reason] == [
+        expected_finish_reason
+    ]
+
+
 def test_mistral_invoke_stream_yields_text_and_finish_reason(
     _aws_test_credentials: None,
 ) -> None:
diff --git a/tests/unit/llms/databricks/chat/test_databricks_chat_transformation.py b/tests/unit/llms/databricks/chat/test_databricks_chat_transformation.py
index d2b78235c29..e04dd35f851 100644
--- a/tests/unit/llms/databricks/chat/test_databricks_chat_transformation.py
+++ b/tests/unit/llms/databricks/chat/test_databricks_chat_transformation.py
@@ -19,6 +19,7 @@ from litellm.constants import (
     DEFAULT_REASONING_EFFORT_HIGH_THINKING_BUDGET,
     DEFAULT_REASONING_EFFORT_LOW_THINKING_BUDGET,
     DEFAULT_REASONING_EFFORT_MEDIUM_THINKING_BUDGET,
+    RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION,
 )
 from litellm.llms.custom_httpx.http_handler import AsyncHTTPHandler, HTTPHandler
 from litellm.llms.databricks.common_utils import DatabricksException
@@ -2591,6 +2592,50 @@ def test_databricks_claude_json_schema_preserves_refs_in_tool_parameters() -> No
     ]
 
 
+@pytest.mark.parametrize(
+    ("model", "thinking_params", "forced"),
+    (
+        ("databricks-claude-opus-5", {}, False),
+        ("databricks-claude-opus-4-8", {"thinking": {"type": "adaptive"}}, False),
+        ("databricks-claude-opus-5-5", {}, False),
+        ("databricks-claude-opus-4-8", {}, True),
+        ("databricks-claude-opus-5", {"thinking": {"type": "disabled"}}, True),
+    ),
+    ids=(
+        "opus-5-default-thinking",
+        "opus-4-8-adaptive",
+        "opus-5-5-without-forced-tools",
+        "opus-4-8-default-off",
+        "opus-5-thinking-disabled",
+    ),
+)
+def test_databricks_claude_json_tool_is_forced_only_when_the_model_will_not_think(
+    local_model_cost_map: None, model: str, thinking_params: dict[str, object], forced: bool
+) -> None:
+    optional_params: Final = litellm.utils.get_optional_params(
+        model=model,
+        custom_llm_provider="databricks",
+        response_format=copy.deepcopy(JSON_SCHEMA_RESPONSE_FORMAT),
+        **thinking_params,
+    )
+    request: Final[dict[str, object]] = TypeAdapter(dict[str, object]).validate_python(
+        DatabricksConfig().transform_request(  # pyright: ignore[reportUnknownMemberType]  # inherited hook is untyped
+            model=model,
+            messages=[{"role": "user", "content": "Name the capital of France."}],
+            optional_params=dict(optional_params),
+            litellm_params={},
+            headers={},
+        )
+    )
+
+    assert (
+        request.get("tool_choice") == {"type": "function", "function": {"name": "json_tool_call"}}
+    ) is forced
+    assert optional_params["tools"][0]["function"].get("description") == (
+        None if forced else RESPONSE_FORMAT_UNFORCED_TOOL_DESCRIPTION
+    )
+
+
 def test_databricks_pydantic_json_schema_preserves_nested_refs() -> None:
     class Person(BaseModel):
         model_config = ConfigDict(frozen=True)
diff --git a/tests/unit/test_main.py b/tests/unit/test_main.py
index 0220495032b..99c6f6c402c 100644
--- a/tests/unit/test_main.py
+++ b/tests/unit/test_main.py
@@ -7703,6 +7703,7 @@ async def test_bedrock_converse_parses_scripted_response(
     assert json.loads(route.calls[0].request.content) == {
         "messages": [{"role": "user", "content": [{"text": "hello"}]}],
         "inferenceConfig": {},
+        "additionalModelResponseFieldPaths": ["/usage/output_tokens_details"],
     }
     assert response.choices[0].message.content == "Hello from Bedrock."
     assert response.usage.prompt_tokens == 8
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index e293b2a5be3..e24499db071 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -1244,6 +1244,7 @@ _COST_MAP_ROW_SCHEMA: Final = {
             "supports_anthropic_thinking_payload": {"type": "boolean"},
             "supports_legacy_thinking": {"type": "boolean"},
             "thinking_always_on": {"type": "boolean"},
+            "thinking_on_by_default": {"type": "boolean"},
             "supports_mid_conversation_system": {"type": "boolean"},
             "supports_sampling_params": {"type": "boolean"},
             "supports_output_config": {"type": "boolean"},