diff --git a/litellm/llms/anthropic/experimental_pass_through/adapters/handler.py b/litellm/llms/anthropic/experimental_pass_through/adapters/handler.py
index 897ca3bf893..d16f5afb45c 100644
--- a/litellm/llms/anthropic/experimental_pass_through/adapters/handler.py
+++ b/litellm/llms/anthropic/experimental_pass_through/adapters/handler.py
@@ -106,6 +106,44 @@ class LiteLLMMessagesToCompletionTransformationHandler:
                     updated_reasoning_effort["summary"] = effective_summary
                     completion_kwargs["reasoning_effort"] = updated_reasoning_effort
 
+    @staticmethod
+    def _normalize_reasoning_effort(
+        completion_kwargs: Dict[str, Any],
+    ) -> None:
+        """
+        Normalize reasoning_effort values based on target model capabilities.
+
+        Handles both string ("max") and dict ({"effort": "max", "summary": ...})
+        formats. Uses model registry to check supports_xhigh/supports_minimal.
+        """
+        from litellm.llms.anthropic.experimental_pass_through.utils import (
+            normalize_reasoning_effort_value,
+        )
+
+        reasoning_effort = completion_kwargs.get("reasoning_effort")
+        if reasoning_effort is None:
+            return
+
+        model = cast(str, completion_kwargs.get("model", ""))
+        custom_llm_provider = completion_kwargs.get("custom_llm_provider")
+
+        if isinstance(reasoning_effort, str):
+            normalized = normalize_reasoning_effort_value(
+                reasoning_effort, model=model, custom_llm_provider=custom_llm_provider
+            )
+            if normalized != reasoning_effort:
+                completion_kwargs["reasoning_effort"] = normalized
+        elif isinstance(reasoning_effort, dict) and "effort" in reasoning_effort:
+            effort = reasoning_effort["effort"]
+            normalized = normalize_reasoning_effort_value(
+                effort, model=model, custom_llm_provider=custom_llm_provider
+            )
+            if normalized != effort:
+                completion_kwargs["reasoning_effort"] = {
+                    **reasoning_effort,
+                    "effort": normalized,
+                }
+
     @staticmethod
     def _prepare_completion_kwargs(
         *,
@@ -163,6 +201,12 @@ class LiteLLMMessagesToCompletionTransformationHandler:
         if output_format:
             request_data["output_format"] = output_format
 
+        # Extract output_config from extra_kwargs so the translator can use it
+        # (e.g. output_config.effort for adaptive thinking → reasoning_effort)
+        extra_kwargs = extra_kwargs or {}
+        if "output_config" in extra_kwargs:
+            request_data["output_config"] = extra_kwargs["output_config"]
+
         (
             openai_request,
             tool_name_mapping,
@@ -202,6 +246,14 @@ class LiteLLMMessagesToCompletionTransformationHandler:
             ):
                 completion_kwargs[key] = value
 
+        # Normalize reasoning_effort based on model capabilities
+        # (e.g. "max" → "xhigh"/"high", "minimal" → "low" if unsupported)
+        # Must run BEFORE _route_openai_thinking, which prepends "responses/"
+        # to the model name and would break get_model_info() lookups.
+        LiteLLMMessagesToCompletionTransformationHandler._normalize_reasoning_effort(
+            completion_kwargs
+        )
+
         LiteLLMMessagesToCompletionTransformationHandler._route_openai_thinking_to_responses_api_if_needed(
             completion_kwargs,
             thinking=thinking,
diff --git a/litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py b/litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py
index 072ae7c3bbe..e5d2b4ce782 100644
--- a/litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py
+++ b/litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py
@@ -317,6 +317,7 @@ class LiteLLMAnthropicMessagesAdapter:
             "tools",
             "thinking",
             "output_format",
+            "output_config",
         ]
 
     def _is_web_search_tool(self, tool: Dict[str, Any]) -> bool:
@@ -694,6 +695,11 @@ class LiteLLMAnthropicMessagesAdapter:
                 return "low"
             else:
                 return "minimal"
+        elif thinking_type == "adaptive":
+            # Adaptive thinking: effort is controlled by output_config.effort,
+            # not budget_tokens. Return a default; caller should override with
+            # output_config.effort when available.
+            return "medium"
 
         return None
 
@@ -1041,6 +1047,12 @@ class LiteLLMAnthropicMessagesAdapter:
         if not reasoning_effort:
             return
 
+        # For adaptive thinking, override with output_config.effort if available
+        if isinstance(thinking, dict) and thinking.get("type") == "adaptive":
+            output_config = anthropic_message_request.get("output_config")
+            if isinstance(output_config, dict) and output_config.get("effort"):
+                reasoning_effort = output_config["effort"]
+
         summary = thinking.get("summary") if isinstance(thinking, dict) else None
         auto_summary = is_reasoning_auto_summary_enabled()
         if summary:
diff --git a/litellm/llms/anthropic/experimental_pass_through/responses_adapters/handler.py b/litellm/llms/anthropic/experimental_pass_through/responses_adapters/handler.py
index 198ebe1ff8c..5be16dcbf16 100644
--- a/litellm/llms/anthropic/experimental_pass_through/responses_adapters/handler.py
+++ b/litellm/llms/anthropic/experimental_pass_through/responses_adapters/handler.py
@@ -72,6 +72,23 @@ def _build_responses_kwargs(
     anthropic_request = AnthropicMessagesRequest(**request_data)  # type: ignore[typeddict-item]
     responses_kwargs = _ADAPTER.translate_request(anthropic_request)
 
+    # Normalize reasoning effort based on model capabilities
+    # (e.g. "max" → "xhigh"/"high", "minimal" → "low" if unsupported)
+    reasoning = responses_kwargs.get("reasoning")
+    if isinstance(reasoning, dict) and "effort" in reasoning:
+        from litellm.llms.anthropic.experimental_pass_through.utils import (
+            normalize_reasoning_effort_value,
+        )
+
+        effort = reasoning["effort"]
+        normalized = normalize_reasoning_effort_value(
+            effort,
+            model=model,
+            custom_llm_provider=(extra_kwargs or {}).get("custom_llm_provider"),
+        )
+        if normalized != effort:
+            responses_kwargs["reasoning"] = {**reasoning, "effort": normalized}
+
     if stream:
         responses_kwargs["stream"] = True
 
diff --git a/litellm/llms/anthropic/experimental_pass_through/responses_adapters/transformation.py b/litellm/llms/anthropic/experimental_pass_through/responses_adapters/transformation.py
index 913470e7088..2badc2a3276 100644
--- a/litellm/llms/anthropic/experimental_pass_through/responses_adapters/transformation.py
+++ b/litellm/llms/anthropic/experimental_pass_through/responses_adapters/transformation.py
@@ -251,25 +251,41 @@ class LiteLLMAnthropicToResponsesAPIAdapter:
 
     @staticmethod
     def translate_thinking_to_reasoning(
-        thinking: Dict[str, Any]
+        thinking: Dict[str, Any],
+        output_config: Optional[Dict[str, Any]] = None,
     ) -> Optional[Dict[str, Any]]:
         """
         Convert Anthropic thinking param to Responses API reasoning param.
 
         thinking.budget_tokens maps to reasoning effort:
           >= 10000 -> high, >= 5000 -> medium, >= 2000 -> low, < 2000 -> minimal
+
+        For adaptive thinking, uses output_config.effort if available,
+        otherwise defaults to medium.
         """
-        if not isinstance(thinking, dict) or thinking.get("type") != "enabled":
+        if not isinstance(thinking, dict):
             return None
-        budget = thinking.get("budget_tokens", 0)
-        if budget >= 10000:
-            effort = "high"
-        elif budget >= 5000:
+
+        thinking_type = thinking.get("type")
+
+        if thinking_type == "adaptive":
+            # Use output_config.effort if available
             effort = "medium"
-        elif budget >= 2000:
-            effort = "low"
+            if isinstance(output_config, dict) and output_config.get("effort"):
+                effort = output_config["effort"]
+        elif thinking_type == "enabled":
+            budget = thinking.get("budget_tokens", 0)
+            if budget >= 10000:
+                effort = "high"
+            elif budget >= 5000:
+                effort = "medium"
+            elif budget >= 2000:
+                effort = "low"
+            else:
+                effort = "minimal"
         else:
-            effort = "minimal"
+            return None
+
         auto_summary = is_reasoning_auto_summary_enabled()
         result: Dict[str, Any] = {"effort": effort}
         summary = thinking.get("summary")
@@ -346,7 +362,11 @@ class LiteLLMAnthropicToResponsesAPIAdapter:
         # thinking -> reasoning
         thinking = anthropic_request.get("thinking")
         if isinstance(thinking, dict):
-            reasoning = self.translate_thinking_to_reasoning(thinking)
+            output_config = anthropic_request.get("output_config")
+            reasoning = self.translate_thinking_to_reasoning(
+                thinking,
+                output_config=cast(Optional[Dict[str, Any]], output_config),
+            )
             if reasoning:
                 responses_kwargs["reasoning"] = reasoning
 
diff --git a/litellm/llms/anthropic/experimental_pass_through/utils.py b/litellm/llms/anthropic/experimental_pass_through/utils.py
index 6c1db6017b2..d975bee0bc2 100644
--- a/litellm/llms/anthropic/experimental_pass_through/utils.py
+++ b/litellm/llms/anthropic/experimental_pass_through/utils.py
@@ -1,4 +1,5 @@
 import os
+from typing import Optional
 
 import litellm
 
@@ -9,3 +10,46 @@ def is_reasoning_auto_summary_enabled() -> bool:
         litellm.reasoning_auto_summary
         or os.getenv("LITELLM_REASONING_AUTO_SUMMARY", "false").lower() == "true"
     )
+
+
+def normalize_reasoning_effort_value(
+    effort: str,
+    model: str,
+    custom_llm_provider: Optional[str] = None,
+) -> str:
+    """
+    Normalize a reasoning effort value based on model capabilities.
+
+    Degradation chains:
+    - "max"     → max / xhigh / high
+    - "xhigh"   → xhigh / high
+    - "minimal" → minimal / low
+    - other values pass through unchanged
+    """
+    if effort not in ("max", "xhigh", "minimal"):
+        return effort
+
+    from litellm.utils import get_model_info
+
+    try:
+        model_info = get_model_info(
+            model=model, custom_llm_provider=custom_llm_provider
+        )
+    except Exception:
+        model_info = {}
+
+    if effort == "max":
+        if model_info.get("supports_max_reasoning_effort"):
+            return "max"
+        if model_info.get("supports_xhigh_reasoning_effort"):
+            return "xhigh"
+        return "high"
+    elif effort == "xhigh":
+        if model_info.get("supports_xhigh_reasoning_effort"):
+            return "xhigh"
+        return "high"
+    elif effort == "minimal":
+        if model_info.get("supports_minimal_reasoning_effort"):
+            return "minimal"
+        return "low"
+    return "medium"
diff --git a/litellm/model_prices_and_context_window_backup.json b/litellm/model_prices_and_context_window_backup.json
index 04b68b8f4ec..05b59d45f99 100644
--- a/litellm/model_prices_and_context_window_backup.json
+++ b/litellm/model_prices_and_context_window_backup.json
@@ -1006,7 +1006,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "global.anthropic.claude-opus-4-6-v1": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -1034,7 +1035,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "us.anthropic.claude-opus-4-6-v1": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1062,7 +1064,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "eu.anthropic.claude-opus-4-6-v1": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1090,7 +1093,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "au.anthropic.claude-opus-4-6-v1": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1118,7 +1122,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -1146,7 +1151,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "global.anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -1174,7 +1181,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "us.anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1202,7 +1211,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "eu.anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1230,7 +1241,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "au.anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1258,7 +1271,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -1285,7 +1300,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "global.anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -1312,7 +1328,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "us.anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 4.125e-06,
@@ -1339,7 +1356,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "eu.anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 4.125e-06,
@@ -1366,7 +1384,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "au.anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 4.125e-06,
@@ -1393,7 +1412,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "anthropic.claude-sonnet-4-20250514-v1:0": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -1911,7 +1931,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 159,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "azure_ai/claude-opus-4-7": {
         "input_cost_per_token": 5e-06,
@@ -1939,7 +1960,9 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
-        "tool_use_system_prompt_tokens": 159
+        "tool_use_system_prompt_tokens": 159,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "azure_ai/claude-opus-4-1": {
         "cache_creation_input_token_cost": 1.875e-05,
@@ -2003,7 +2026,8 @@
         "supports_response_schema": true,
         "supports_tool_choice": true,
         "supports_vision": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_minimal_reasoning_effort": true
     },
     "azure/computer-use-preview": {
         "input_cost_per_token": 3e-06,
@@ -8909,7 +8933,8 @@
         "supports_response_schema": true,
         "supports_tool_choice": true,
         "supports_vision": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-sonnet-4-5-20250929-v1:0": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -9103,7 +9128,8 @@
             "us": 1.1,
             "fast": 6.0
         },
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-opus-4-6-20260205": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -9135,7 +9161,8 @@
             "us": 1.1,
             "fast": 6.0
         },
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -9167,7 +9194,9 @@
         "provider_specific_entry": {
             "us": 1.1,
             "fast": 6.0
-        }
+        },
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-opus-4-7-20260416": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -9199,7 +9228,9 @@
         "provider_specific_entry": {
             "us": 1.1,
             "fast": 6.0
-        }
+        },
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-sonnet-4-20250514": {
         "deprecation_date": "2026-05-14",
@@ -25052,7 +25083,8 @@
         "supports_reasoning": true,
         "supports_tool_choice": true,
         "supports_vision": true,
-        "tool_use_system_prompt_tokens": 159
+        "tool_use_system_prompt_tokens": 159,
+        "supports_minimal_reasoning_effort": true
     },
     "openrouter/anthropic/claude-opus-4.5": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -25090,7 +25122,8 @@
         "supports_reasoning": true,
         "supports_tool_choice": true,
         "supports_vision": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_minimal_reasoning_effort": true
     },
     "openrouter/anthropic/claude-sonnet-4.5": {
         "input_cost_per_image": 0.0048,
@@ -30118,7 +30151,8 @@
         "supports_reasoning": true,
         "supports_response_schema": true,
         "supports_tool_choice": true,
-        "supports_vision": true
+        "supports_vision": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vercel_ai_gateway/anthropic/claude-sonnet-4": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -31345,7 +31379,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-opus-4-6@default": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -31372,7 +31407,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -31399,7 +31435,9 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-opus-4-7@default": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -31426,7 +31464,9 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-sonnet-4-5": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -31478,7 +31518,8 @@
             "search_context_size_high": 0.01,
             "search_context_size_low": 0.01,
             "search_context_size_medium": 0.01
-        }
+        },
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-sonnet-4-5@20250929": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -38345,7 +38386,8 @@
             "search_context_size_high": 0.01,
             "search_context_size_low": 0.01,
             "search_context_size_medium": 0.01
-        }
+        },
+        "supports_minimal_reasoning_effort": true
     },
     "duckduckgo/search": {
         "litellm_provider": "duckduckgo",
diff --git a/litellm/types/utils.py b/litellm/types/utils.py
index e3058d106a6..c347956cba7 100644
--- a/litellm/types/utils.py
+++ b/litellm/types/utils.py
@@ -139,7 +139,9 @@ class ProviderSpecificModelInfo(TypedDict, total=False):
     supports_reasoning: Optional[bool]
     supports_url_context: Optional[bool]
     supports_none_reasoning_effort: Optional[bool]
+    supports_minimal_reasoning_effort: Optional[bool]
     supports_xhigh_reasoning_effort: Optional[bool]
+    supports_max_reasoning_effort: Optional[bool]
 
 
 class SearchContextCostPerQuery(TypedDict, total=False):
diff --git a/litellm/utils.py b/litellm/utils.py
index c4aee792972..7a9f62afa09 100644
--- a/litellm/utils.py
+++ b/litellm/utils.py
@@ -5893,9 +5893,15 @@ def _get_model_info_helper(  # noqa: PLR0915
                 supports_none_reasoning_effort=_model_info.get(
                     "supports_none_reasoning_effort", None
                 ),
+                supports_minimal_reasoning_effort=_model_info.get(
+                    "supports_minimal_reasoning_effort", None
+                ),
                 supports_xhigh_reasoning_effort=_model_info.get(
                     "supports_xhigh_reasoning_effort", None
                 ),
+                supports_max_reasoning_effort=_model_info.get(
+                    "supports_max_reasoning_effort", None
+                ),
                 supports_computer_use=_model_info.get("supports_computer_use", None),
                 search_context_cost_per_query=_model_info.get(
                     "search_context_cost_per_query", None
diff --git a/model_prices_and_context_window.json b/model_prices_and_context_window.json
index 386532f07a3..8a28235f985 100644
--- a/model_prices_and_context_window.json
+++ b/model_prices_and_context_window.json
@@ -1006,7 +1006,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "global.anthropic.claude-opus-4-6-v1": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -1034,7 +1035,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "us.anthropic.claude-opus-4-6-v1": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1062,7 +1064,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "eu.anthropic.claude-opus-4-6-v1": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1090,7 +1093,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "au.anthropic.claude-opus-4-6-v1": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1118,7 +1122,8 @@
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
         "supports_native_structured_output": true,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -1146,7 +1151,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "anthropic.claude-mythos-preview": {
         "input_cost_per_token": 0,
@@ -1188,7 +1195,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "us.anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1216,7 +1225,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "eu.anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1244,7 +1255,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "au.anthropic.claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.875e-06,
@@ -1272,7 +1285,9 @@
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -1299,7 +1314,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "global.anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -1326,7 +1342,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "us.anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 4.125e-06,
@@ -1353,7 +1370,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "eu.anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 4.125e-06,
@@ -1380,7 +1398,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "au.anthropic.claude-sonnet-4-6": {
         "cache_creation_input_token_cost": 4.125e-06,
@@ -1407,7 +1426,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_native_structured_output": true
+        "supports_native_structured_output": true,
+        "supports_minimal_reasoning_effort": true
     },
     "anthropic.claude-sonnet-4-20250514-v1:0": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -1925,7 +1945,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 159,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "azure_ai/claude-opus-4-7": {
         "input_cost_per_token": 5e-06,
@@ -1953,7 +1974,9 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
-        "tool_use_system_prompt_tokens": 159
+        "tool_use_system_prompt_tokens": 159,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "azure_ai/claude-opus-4-1": {
         "cache_creation_input_token_cost": 1.875e-05,
@@ -2017,7 +2040,8 @@
         "supports_response_schema": true,
         "supports_tool_choice": true,
         "supports_vision": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_minimal_reasoning_effort": true
     },
     "azure/computer-use-preview": {
         "input_cost_per_token": 3e-06,
@@ -8923,7 +8947,8 @@
         "supports_response_schema": true,
         "supports_tool_choice": true,
         "supports_vision": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-sonnet-4-5-20250929-v1:0": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -9117,7 +9142,8 @@
             "us": 1.1,
             "fast": 6.0
         },
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-opus-4-6-20260205": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -9149,7 +9175,8 @@
             "us": 1.1,
             "fast": 6.0
         },
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -9181,7 +9208,9 @@
         "provider_specific_entry": {
             "us": 1.1,
             "fast": 6.0
-        }
+        },
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-opus-4-7-20260416": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -9213,7 +9242,9 @@
         "provider_specific_entry": {
             "us": 1.1,
             "fast": 6.0
-        }
+        },
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "claude-sonnet-4-20250514": {
         "deprecation_date": "2026-05-14",
@@ -25066,7 +25097,8 @@
         "supports_reasoning": true,
         "supports_tool_choice": true,
         "supports_vision": true,
-        "tool_use_system_prompt_tokens": 159
+        "tool_use_system_prompt_tokens": 159,
+        "supports_minimal_reasoning_effort": true
     },
     "openrouter/anthropic/claude-opus-4.5": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -25104,7 +25136,8 @@
         "supports_reasoning": true,
         "supports_tool_choice": true,
         "supports_vision": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_minimal_reasoning_effort": true
     },
     "openrouter/anthropic/claude-sonnet-4.5": {
         "input_cost_per_image": 0.0048,
@@ -30132,7 +30165,8 @@
         "supports_reasoning": true,
         "supports_response_schema": true,
         "supports_tool_choice": true,
-        "supports_vision": true
+        "supports_vision": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vercel_ai_gateway/anthropic/claude-sonnet-4": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -31359,7 +31393,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-opus-4-6@default": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -31386,7 +31421,8 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "tool_use_system_prompt_tokens": 346,
-        "supports_max_reasoning_effort": true
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-opus-4-7": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -31413,7 +31449,9 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-opus-4-7@default": {
         "cache_creation_input_token_cost": 6.25e-06,
@@ -31440,7 +31478,9 @@
         "supports_tool_choice": true,
         "supports_vision": true,
         "supports_xhigh_reasoning_effort": true,
-        "tool_use_system_prompt_tokens": 346
+        "tool_use_system_prompt_tokens": 346,
+        "supports_max_reasoning_effort": true,
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-sonnet-4-5": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -31492,7 +31532,8 @@
             "search_context_size_high": 0.01,
             "search_context_size_low": 0.01,
             "search_context_size_medium": 0.01
-        }
+        },
+        "supports_minimal_reasoning_effort": true
     },
     "vertex_ai/claude-sonnet-4-5@20250929": {
         "cache_creation_input_token_cost": 3.75e-06,
@@ -38386,7 +38427,8 @@
             "search_context_size_high": 0.01,
             "search_context_size_low": 0.01,
             "search_context_size_medium": 0.01
-        }
+        },
+        "supports_minimal_reasoning_effort": true
     },
     "duckduckgo/search": {
         "litellm_provider": "duckduckgo",
diff --git a/tests/test_litellm/llms/anthropic/experimental_pass_through/test_reasoning_effort_fields.py b/tests/test_litellm/llms/anthropic/experimental_pass_through/test_reasoning_effort_fields.py
new file mode 100644
index 00000000000..d42d109f21b
--- /dev/null
+++ b/tests/test_litellm/llms/anthropic/experimental_pass_through/test_reasoning_effort_fields.py
@@ -0,0 +1,287 @@
+"""
+Tests for reasoning effort capability fields and normalize_reasoning_effort_value.
+
+Covers:
+- Commit 1: get_model_info returns supports_minimal/supports_max fields
+- Commit 2: Model registry entries have correct reasoning effort fields
+- Commit 3: normalize_reasoning_effort_value degradation chains + adapter translation
+"""
+
+import json
+import os
+from typing import Any, Dict, Optional
+from unittest.mock import patch
+
+import pytest
+
+from litellm.llms.anthropic.experimental_pass_through.utils import (
+    normalize_reasoning_effort_value,
+)
+from litellm.utils import get_model_info
+
+
+def _load_model_registry() -> Dict[str, Any]:
+    """Load the root model_prices_and_context_window.json."""
+    json_path = os.path.join(
+        os.path.dirname(__file__),
+        "../../../../../model_prices_and_context_window.json",
+    )
+    with open(json_path) as f:
+        return json.load(f)
+
+
+# ---------------------------------------------------------------------------
+# Commit 1: get_model_info returns supports_minimal and supports_max fields
+# ---------------------------------------------------------------------------
+
+
+class TestGetModelInfoReasoningEffortFields:
+    """get_model_info should expose supports_minimal_reasoning_effort and
+    supports_max_reasoning_effort from the model registry."""
+
+    def test_opus_4_6_has_supports_minimal(self):
+        info = get_model_info("claude-opus-4-6")
+        assert "supports_minimal_reasoning_effort" in info
+
+    def test_opus_4_6_has_supports_max(self):
+        info = get_model_info("claude-opus-4-6")
+        assert "supports_max_reasoning_effort" in info
+
+    def test_opus_4_7_has_supports_minimal(self):
+        info = get_model_info("claude-opus-4-7")
+        assert "supports_minimal_reasoning_effort" in info
+
+    def test_opus_4_7_has_supports_max(self):
+        info = get_model_info("claude-opus-4-7")
+        assert "supports_max_reasoning_effort" in info
+
+
+# ---------------------------------------------------------------------------
+# Commit 2: JSON registry has correct reasoning effort fields
+# ---------------------------------------------------------------------------
+
+
+class TestModelRegistryReasoningEffortFields:
+    """Verify specific models have the expected reasoning effort capability
+    values in the JSON registry file."""
+
+    @pytest.fixture(autouse=True)
+    def _load_registry(self):
+        self.registry = _load_model_registry()
+
+    def test_opus_4_7_supports_max(self):
+        entry = self.registry["claude-opus-4-7"]
+        assert entry.get("supports_max_reasoning_effort") is True
+
+    def test_opus_4_6_supports_max(self):
+        entry = self.registry["claude-opus-4-6"]
+        assert entry.get("supports_max_reasoning_effort") is True
+
+    def test_opus_4_7_supports_minimal(self):
+        entry = self.registry["claude-opus-4-7"]
+        assert entry.get("supports_minimal_reasoning_effort") is True
+
+    def test_opus_4_6_supports_minimal(self):
+        entry = self.registry["claude-opus-4-6"]
+        assert entry.get("supports_minimal_reasoning_effort") is True
+
+    def test_sonnet_4_6_supports_minimal(self):
+        entry = self.registry["anthropic.claude-sonnet-4-6"]
+        assert entry.get("supports_minimal_reasoning_effort") is True
+
+    def test_bedrock_opus_4_7_supports_max(self):
+        entry = self.registry["anthropic.claude-opus-4-7"]
+        assert entry.get("supports_max_reasoning_effort") is True
+        assert entry.get("supports_minimal_reasoning_effort") is True
+
+    def test_vertex_opus_4_7_supports_max(self):
+        entry = self.registry["vertex_ai/claude-opus-4-7"]
+        assert entry.get("supports_max_reasoning_effort") is True
+        assert entry.get("supports_minimal_reasoning_effort") is True
+
+    def test_vertex_opus_4_6_supports_max(self):
+        entry = self.registry["vertex_ai/claude-opus-4-6"]
+        assert entry.get("supports_max_reasoning_effort") is True
+        assert entry.get("supports_minimal_reasoning_effort") is True
+
+    def test_azure_ai_opus_4_6_supports_minimal(self):
+        entry = self.registry["azure_ai/claude-opus-4-6"]
+        assert entry.get("supports_minimal_reasoning_effort") is True
+
+    def test_azure_ai_opus_4_7_supports_max(self):
+        entry = self.registry["azure_ai/claude-opus-4-7"]
+        assert entry.get("supports_max_reasoning_effort") is True
+        assert entry.get("supports_minimal_reasoning_effort") is True
+
+
+# ---------------------------------------------------------------------------
+# Commit 3: normalize_reasoning_effort_value
+# ---------------------------------------------------------------------------
+
+
+def _mock_model_info(**flags):
+    """Return a mock model_info dict with given capability flags."""
+    return flags
+
+
+class TestNormalizeReasoningEffortValue:
+    """Test degradation chains for normalize_reasoning_effort_value."""
+
+    # --- "max" degradation chain ---
+
+    def test_max_stays_max_when_supported(self):
+        with patch(
+            "litellm.utils.get_model_info",
+            return_value=_mock_model_info(
+                supports_max_reasoning_effort=True,
+                supports_xhigh_reasoning_effort=True,
+            ),
+        ):
+            assert normalize_reasoning_effort_value("max", model="test") == "max"
+
+    def test_max_degrades_to_xhigh(self):
+        with patch(
+            "litellm.utils.get_model_info",
+            return_value=_mock_model_info(
+                supports_max_reasoning_effort=False,
+                supports_xhigh_reasoning_effort=True,
+            ),
+        ):
+            assert normalize_reasoning_effort_value("max", model="test") == "xhigh"
+
+    def test_max_degrades_to_high(self):
+        with patch(
+            "litellm.utils.get_model_info",
+            return_value=_mock_model_info(
+                supports_max_reasoning_effort=False,
+                supports_xhigh_reasoning_effort=False,
+            ),
+        ):
+            assert normalize_reasoning_effort_value("max", model="test") == "high"
+
+    # --- "xhigh" degradation chain ---
+
+    def test_xhigh_stays_xhigh_when_supported(self):
+        with patch(
+            "litellm.utils.get_model_info",
+            return_value=_mock_model_info(supports_xhigh_reasoning_effort=True),
+        ):
+            assert normalize_reasoning_effort_value("xhigh", model="test") == "xhigh"
+
+    def test_xhigh_degrades_to_high(self):
+        with patch(
+            "litellm.utils.get_model_info",
+            return_value=_mock_model_info(supports_xhigh_reasoning_effort=False),
+        ):
+            assert normalize_reasoning_effort_value("xhigh", model="test") == "high"
+
+    # --- "minimal" degradation chain ---
+
+    def test_minimal_stays_minimal_when_supported(self):
+        with patch(
+            "litellm.utils.get_model_info",
+            return_value=_mock_model_info(supports_minimal_reasoning_effort=True),
+        ):
+            assert (
+                normalize_reasoning_effort_value("minimal", model="test") == "minimal"
+            )
+
+    def test_minimal_degrades_to_low(self):
+        with patch(
+            "litellm.utils.get_model_info",
+            return_value=_mock_model_info(supports_minimal_reasoning_effort=False),
+        ):
+            assert normalize_reasoning_effort_value("minimal", model="test") == "low"
+
+    # --- passthrough values ---
+
+    def test_high_passes_through(self):
+        assert normalize_reasoning_effort_value("high", model="test") == "high"
+
+    def test_medium_passes_through(self):
+        assert normalize_reasoning_effort_value("medium", model="test") == "medium"
+
+    def test_low_passes_through(self):
+        assert normalize_reasoning_effort_value("low", model="test") == "low"
+
+    # --- exception fallback ---
+
+    def test_exception_fallback_uses_empty_model_info(self):
+        """When get_model_info raises, treat model_info as {} (no capabilities)."""
+        with patch(
+            "litellm.utils.get_model_info",
+            side_effect=Exception("model not found"),
+        ):
+            # "max" with no capabilities -> "high"
+            assert normalize_reasoning_effort_value("max", model="unknown") == "high"
+            # "minimal" with no capabilities -> "low"
+            assert normalize_reasoning_effort_value("minimal", model="unknown") == "low"
+
+
+# ---------------------------------------------------------------------------
+# Commit 3: Adapter translation — adaptive thinking + output_config.effort
+# ---------------------------------------------------------------------------
+
+
+class TestAdapterAdaptiveThinking:
+    """Test that adaptive thinking type maps correctly through the adapters."""
+
+    def test_messages_adapter_adaptive_returns_medium_default(self):
+        """Adaptive thinking returns 'medium' as default reasoning_effort."""
+        from litellm.llms.anthropic.experimental_pass_through.adapters.transformation import (
+            LiteLLMAnthropicMessagesAdapter,
+        )
+
+        adapter = LiteLLMAnthropicMessagesAdapter()
+        result = adapter.translate_anthropic_thinking_to_reasoning_effort(
+            {"type": "adaptive"}
+        )
+        assert result == "medium"
+
+    def test_messages_adapter_adaptive_overridden_by_output_config(self):
+        """For adaptive thinking, output_config.effort overrides reasoning_effort."""
+        from litellm.llms.anthropic.experimental_pass_through.adapters.transformation import (
+            LiteLLMAnthropicMessagesAdapter,
+        )
+        from litellm.types.llms.anthropic import AnthropicMessagesRequest
+
+        adapter = LiteLLMAnthropicMessagesAdapter()
+        request = AnthropicMessagesRequest(
+            model="test-model",
+            messages=[{"role": "user", "content": "hello"}],
+            max_tokens=1024,
+            thinking={"type": "adaptive"},
+            output_config={"effort": "high"},
+        )
+        openai_kwargs, _ = adapter.translate_anthropic_to_openai(request)
+        # reasoning_effort should be set (either as string or dict with effort)
+        re = openai_kwargs.get("reasoning_effort")
+        if isinstance(re, dict):
+            assert re["effort"] == "high"
+        else:
+            assert re == "high"
+
+    def test_responses_adapter_adaptive_with_output_config(self):
+        """Responses adapter: adaptive thinking + output_config.effort."""
+        from litellm.llms.anthropic.experimental_pass_through.responses_adapters.transformation import (
+            LiteLLMAnthropicToResponsesAPIAdapter,
+        )
+
+        result = LiteLLMAnthropicToResponsesAPIAdapter.translate_thinking_to_reasoning(
+            thinking={"type": "adaptive"},
+            output_config={"effort": "xhigh"},
+        )
+        assert result is not None
+        assert result["effort"] == "xhigh"
+
+    def test_responses_adapter_adaptive_default_medium(self):
+        """Responses adapter: adaptive thinking without output_config defaults to medium."""
+        from litellm.llms.anthropic.experimental_pass_through.responses_adapters.transformation import (
+            LiteLLMAnthropicToResponsesAPIAdapter,
+        )
+
+        result = LiteLLMAnthropicToResponsesAPIAdapter.translate_thinking_to_reasoning(
+            thinking={"type": "adaptive"},
+        )
+        assert result is not None
+        assert result["effort"] == "medium"