diff --git a/litellm-rust/crates/inference-messages/src/types.rs b/litellm-rust/crates/inference-messages/src/types.rs
index ae346259559..638f709f265 100644
--- a/litellm-rust/crates/inference-messages/src/types.rs
+++ b/litellm-rust/crates/inference-messages/src/types.rs
@@ -122,6 +122,7 @@ mod tests {
                 "supports_reasoning": true,
                 "supports_adaptive_thinking": true,
                 "thinking_always_on": false,
+                "thinking_on_by_default": true,
                 "supports_legacy_thinking": false,
                 "supports_output_config": true,
                 "supports_sampling_params": false,
@@ -144,6 +145,7 @@ mod tests {
                 supports_reasoning: true,
                 supports_adaptive_thinking: true,
                 thinking_always_on: false,
+                thinking_on_by_default: true,
                 supports_legacy_thinking: false,
                 supports_output_config: true,
                 supports_sampling_params: false,
diff --git a/litellm-rust/crates/llms/src/anthropic/common_utils.rs b/litellm-rust/crates/llms/src/anthropic/common_utils.rs
index 7991a57353e..f2d73363644 100644
--- a/litellm-rust/crates/llms/src/anthropic/common_utils.rs
+++ b/litellm-rust/crates/llms/src/anthropic/common_utils.rs
@@ -1880,6 +1880,7 @@ mod tests {
                 supports_reasoning: false,
                 supports_adaptive_thinking: false,
                 thinking_always_on: false,
+                thinking_on_by_default: false,
                 supports_legacy_thinking: false,
                 supports_output_config: false,
                 supports_sampling_params: true,
diff --git a/litellm-rust/crates/llms/src/anthropic/messages/thinking.rs b/litellm-rust/crates/llms/src/anthropic/messages/thinking.rs
index e21711dc40d..fd0c07cd9a4 100644
--- a/litellm-rust/crates/llms/src/anthropic/messages/thinking.rs
+++ b/litellm-rust/crates/llms/src/anthropic/messages/thinking.rs
@@ -184,7 +184,9 @@ fn without_thinking(
     params: MessagesOptionalParams,
     context: &ThinkingContext,
 ) -> MessagesOptionalParams {
-    let context_management = if context.capabilities.thinking_always_on {
+    let thinks_without_thinking_param =
+        context.capabilities.thinking_always_on || context.capabilities.thinking_on_by_default;
+    let context_management = if thinks_without_thinking_param {
         params.context_management
     } else {
         without_clear_thinking_edits(params.context_management)
@@ -515,6 +517,14 @@ mod tests {
         }
     }
 
+    #[fixture]
+    fn sonnet_5() -> MessagesModelCapabilities {
+        MessagesModelCapabilities {
+            thinking_on_by_default: true,
+            ..opus_4_7()
+        }
+    }
+
     #[fixture]
     fn newfamily_6() -> MessagesModelCapabilities {
         MessagesModelCapabilities {
@@ -716,7 +726,17 @@ mod tests {
         serde_json::json!({"max_tokens": 8192, "reasoning_effort": "none"}),
         true
     )]
-    fn clear_thinking_edit_is_dropped_with_thinking_except_on_always_on_models(
+    #[case::default_thinking_model_keeps_edit(
+        sonnet_5(),
+        serde_json::json!({"max_tokens": 8192, "reasoning_effort": "none"}),
+        true
+    )]
+    #[case::adaptive_model_without_default_thinking_drops_edit(
+        opus_4_7(),
+        serde_json::json!({"max_tokens": 8192, "reasoning_effort": "none"}),
+        false
+    )]
+    fn clear_thinking_edit_is_dropped_with_thinking_except_on_models_that_think_by_default(
         #[case] capabilities: MessagesModelCapabilities,
         #[case] fields: Value,
         #[case] keeps_edit: bool,
@@ -726,7 +746,8 @@ mod tests {
             "context_management".into(),
             serde_json::json!({"edits": [{"type": "clear_thinking_20251015", "keep": "all"}, {"type": "clear_tool_uses_20250919"}]}),
         );
-        let always_on = capabilities.thinking_always_on;
+        let thinks_without_thinking_param =
+            capabilities.thinking_always_on || capabilities.thinking_on_by_default;
         let translated = serde_json::to_value(translate(capabilities, fields).unwrap()).unwrap();
         let edit_types: Vec<&str> = translated["context_management"]["edits"]
             .as_array()
@@ -742,7 +763,7 @@ mod tests {
         assert_eq!(edit_types, expected);
         assert_eq!(
             translated.get("thinking").is_some(),
-            keeps_edit && !always_on
+            keeps_edit && !thinks_without_thinking_param
         );
     }
 
diff --git a/litellm-rust/crates/llms/src/base_llm/messages/context.rs b/litellm-rust/crates/llms/src/base_llm/messages/context.rs
index e59a63813b0..1af17f9b975 100644
--- a/litellm-rust/crates/llms/src/base_llm/messages/context.rs
+++ b/litellm-rust/crates/llms/src/base_llm/messages/context.rs
@@ -32,6 +32,8 @@ pub struct MessagesModelCapabilities {
     #[serde(default)]
     pub thinking_always_on: bool,
     #[serde(default)]
+    pub thinking_on_by_default: bool,
+    #[serde(default)]
     pub supports_legacy_thinking: bool,
     #[serde(default)]
     pub supports_output_config: bool,
@@ -55,6 +57,7 @@ impl Default for MessagesModelCapabilities {
             supports_reasoning: false,
             supports_adaptive_thinking: false,
             thinking_always_on: false,
+            thinking_on_by_default: false,
             supports_legacy_thinking: false,
             supports_output_config: false,
             supports_sampling_params: true,
diff --git a/litellm-rust/crates/model-catalog/src/model_info.rs b/litellm-rust/crates/model-catalog/src/model_info.rs
index 8f7549c1c6d..6e0ab177d1e 100644
--- a/litellm-rust/crates/model-catalog/src/model_info.rs
+++ b/litellm-rust/crates/model-catalog/src/model_info.rs
@@ -155,6 +155,7 @@ pub struct ModelInfoFields {
     pub supports_adaptive_thinking: Option<bool>,
     pub supports_legacy_thinking: Option<bool>,
     pub thinking_always_on: Option<bool>,
+    pub thinking_on_by_default: Option<bool>,
     pub supports_tool_search: Option<bool>,
     pub supports_mid_conversation_system: Option<bool>,
     pub supports_anthropic_thinking_payload: Option<bool>,
diff --git a/litellm-rust/crates/model-catalog/src/wire/attributes.rs b/litellm-rust/crates/model-catalog/src/wire/attributes.rs
index 93c10a81524..2d47c1fdb0d 100644
--- a/litellm-rust/crates/model-catalog/src/wire/attributes.rs
+++ b/litellm-rust/crates/model-catalog/src/wire/attributes.rs
@@ -104,6 +104,7 @@ attributes! {
     /// Cloud regions the model is available in ('global' or region ids).
     supported_regions: Vec<String>,
     thinking_always_on: bool,
+    thinking_on_by_default: bool,
     token_count_framing: u64 as Count,
     token_count_model: TokenCountModel,
     token_count_tokenizer: TokenCountTokenizer,
diff --git a/litellm/llms/anthropic/common_utils.py b/litellm/llms/anthropic/common_utils.py
index 4f609c7759a..59fdc9a5791 100644
--- a/litellm/llms/anthropic/common_utils.py
+++ b/litellm/llms/anthropic/common_utils.py
@@ -1819,8 +1819,12 @@ def drop_clear_thinking_edits_for_model(
     model: str,
     custom_llm_provider: str,
 ) -> None:
-    """Remove the clear_thinking edits unless the model always thinks anyway."""
-    if not AnthropicModelInfo.supports_model_capability(model, "thinking_always_on", custom_llm_provider):
+    """Remove the clear_thinking edits unless the model still thinks without a ``thinking`` param."""
+    thinks_without_thinking_param: Final = any(
+        AnthropicModelInfo.supports_model_capability(model, capability, custom_llm_provider)
+        for capability in ("thinking_always_on", "thinking_on_by_default")
+    )
+    if not thinks_without_thinking_param:
         drop_clear_thinking_edits(params)
 
 
diff --git a/litellm/llms/bedrock_mantle/messages/transformation.py b/litellm/llms/bedrock_mantle/messages/transformation.py
index 2ce1a7a4e81..68f75d3c206 100644
--- a/litellm/llms/bedrock_mantle/messages/transformation.py
+++ b/litellm/llms/bedrock_mantle/messages/transformation.py
@@ -1,4 +1,4 @@
-from collections.abc import Mapping
+from collections.abc import Mapping, MutableMapping
 from types import MappingProxyType
 from typing import Final
 
@@ -46,21 +46,21 @@ class BedrockMantleAnthropicMessagesConfig(BedrockMantleAuthMixin, AmazonMantleM
         }
     )
 
-    def _ensure_thinking_for_clear_thinking_context_management(
+    def _drop_thinking(
         self,
-        anthropic_messages_request: dict[str, object],  # mutable-ok: edits the request in place like the base
+        optional_params: MutableMapping[str, object],  # mutable-ok: edits optional params in place
         model: str,
-        drop_params: bool,
-    ) -> bool:
-        injected_thinking: Final = super()._ensure_thinking_for_clear_thinking_context_management(
-            anthropic_messages_request, model, drop_params
-        )
-        match anthropic_messages_request.get("thinking"):
-            case {"type": "enabled" | "adaptive"}:
-                pass
-            case _:
-                drop_clear_thinking_edits_for_model(anthropic_messages_request, model, self._resolved_provider)
-        return injected_thinking
+        custom_llm_provider: str,
+    ) -> None:
+        super()._drop_thinking(optional_params, model, custom_llm_provider)
+        if not self._adds_thinking_back_for_clear_thinking(optional_params, model):
+            drop_clear_thinking_edits_for_model(optional_params, model, custom_llm_provider)
+
+    def _adds_thinking_back_for_clear_thinking(self, optional_params: Mapping[str, object], model: str) -> bool:
+        trial_request: Final = {
+            key: optional_params[key] for key in ("context_management", "max_tokens") if key in optional_params
+        }
+        return self._ensure_thinking_for_clear_thinking_context_management(trial_request, model, drop_params=False)
 
     def __init__(self, aws_signer: BaseAWSLLM | None = None) -> None:
         AmazonMantleMessagesConfig.__init__(self)
diff --git a/litellm/model_prices_and_context_window_backup.json b/litellm/model_prices_and_context_window_backup.json
index 23c6ccf9c0a..8d0a063dab5 100644
--- a/litellm/model_prices_and_context_window_backup.json
+++ b/litellm/model_prices_and_context_window_backup.json
@@ -1939,6 +1939,7 @@
     "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,
@@ -2025,6 +2026,7 @@
     "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,
@@ -2111,6 +2113,7 @@
     "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,
@@ -2197,6 +2200,7 @@
     "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,
@@ -2278,6 +2282,7 @@
     "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,
@@ -2364,6 +2369,7 @@
     "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,
@@ -2760,6 +2766,7 @@
             "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,
@@ -2804,6 +2811,7 @@
             "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,
@@ -2848,6 +2856,7 @@
             "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,
@@ -2892,6 +2901,7 @@
             "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,
@@ -2936,6 +2946,7 @@
             "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,
@@ -2980,6 +2991,7 @@
             "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,
@@ -3827,6 +3839,7 @@
         "deprecation_date": "2027-07-08",
         "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",
@@ -3964,6 +3977,7 @@
             "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,
@@ -15928,6 +15942,7 @@
             "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,
@@ -16461,6 +16476,7 @@
             "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,
@@ -21268,6 +21284,7 @@
         "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,
@@ -21425,6 +21442,7 @@
         "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,
@@ -32864,6 +32882,7 @@
             "/v1/messages"
         ],
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_parallel_function_calling": true,
         "supports_reasoning": true,
@@ -32931,6 +32950,7 @@
             "/v1/messages"
         ],
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_parallel_function_calling": true,
         "supports_reasoning": true,
@@ -32974,6 +32994,7 @@
             "/v1/messages"
         ],
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_parallel_function_calling": true,
         "supports_reasoning": true,
@@ -49051,6 +49072,7 @@
         "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,
@@ -49128,6 +49150,7 @@
         "prompt_cache_min_tokens": 512,
         "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,
@@ -51528,6 +51551,7 @@
         "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,
@@ -51566,6 +51590,7 @@
         "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,
@@ -51809,6 +51834,7 @@
             "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,
@@ -59133,6 +59159,7 @@
             "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,
@@ -65209,6 +65236,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://deepinfra.com/pricing",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
@@ -65524,6 +65552,7 @@
         "prompt_cache_min_tokens": 1024,
         "source": "https://deepinfra.com/pricing",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
@@ -67521,6 +67550,7 @@
         "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,
@@ -67596,6 +67626,7 @@
         "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,
@@ -67809,6 +67840,7 @@
         "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,
@@ -67874,6 +67906,7 @@
         "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,
@@ -68711,6 +68744,7 @@
         "litellm_provider": "perplexity",
         "mode": "responses",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "prompt_cache_min_tokens": 512,
         "supports_web_search": true,
         "supports_function_calling": true,
@@ -68734,6 +68768,7 @@
         "litellm_provider": "perplexity",
         "mode": "responses",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_web_search": true,
         "supports_function_calling": true,
         "input_cost_per_token": 2e-06,
@@ -70810,6 +70845,7 @@
         "supports_vision": true,
         "supports_web_search": true,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "prompt_cache_min_tokens": 512,
         "supports_sampling_params": false
     },
@@ -70830,6 +70866,7 @@
         "supports_vision": true,
         "prompt_cache_min_tokens": 1024,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_sampling_params": false
     },
     "aihubmix/coding-glm-5.3": {
@@ -73453,6 +73490,7 @@
     "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,
@@ -73567,6 +73605,7 @@
         "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,
@@ -75054,6 +75093,7 @@
             "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,
@@ -75106,6 +75146,7 @@
             "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,
@@ -75150,6 +75191,7 @@
         "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,
@@ -75197,6 +75239,7 @@
             "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,
@@ -75233,6 +75276,7 @@
         "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,
@@ -75289,6 +75333,7 @@
             "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,
@@ -75335,6 +75380,7 @@
             "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,
@@ -75375,6 +75421,7 @@
         "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,
@@ -75416,6 +75463,7 @@
         "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,
@@ -75462,6 +75510,7 @@
             "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,
@@ -75513,6 +75562,7 @@
             "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,
@@ -75559,6 +75609,7 @@
             "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,
@@ -75586,6 +75637,7 @@
         "litellm_provider": "perplexity",
         "mode": "responses",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_web_search": true,
         "supports_function_calling": true,
         "input_cost_per_token": 1e-07,
@@ -75616,6 +75668,7 @@
         "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,
@@ -75667,6 +75720,7 @@
             "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,
@@ -75717,6 +75771,7 @@
             "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,
@@ -75761,6 +75816,7 @@
             "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,
@@ -77516,6 +77572,7 @@
             "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,
@@ -77730,6 +77787,7 @@
             "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,
@@ -77894,6 +77952,7 @@
             "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,
@@ -78362,6 +78421,7 @@
         "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/rust_bridge/host/model_capabilities.py b/litellm/rust_bridge/host/model_capabilities.py
index cbf59dfb97b..321a6de8581 100644
--- a/litellm/rust_bridge/host/model_capabilities.py
+++ b/litellm/rust_bridge/host/model_capabilities.py
@@ -27,6 +27,7 @@ def anthropic_model_capabilities(model: str, custom_llm_provider: str | None) ->
         "supports_reasoning": supports("supports_reasoning"),
         "supports_adaptive_thinking": supports("supports_adaptive_thinking"),
         "thinking_always_on": supports("thinking_always_on"),
+        "thinking_on_by_default": supports("thinking_on_by_default"),
         "supports_legacy_thinking": supports("supports_legacy_thinking"),
         "supports_output_config": supports("supports_output_config"),
         "supports_sampling_params": AnthropicModelInfo._supports_sampling_params(resolved_model),  # pyright: ignore[reportPrivateUsage]  # same gate the handler applies
diff --git a/litellm/types/utils.py b/litellm/types/utils.py
index 70ca05904ef..eb2bc6ff89f 100644
--- a/litellm/types/utils.py
+++ b/litellm/types/utils.py
@@ -216,6 +216,7 @@ 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 72c37c3760e..a02031a26f3 100644
--- a/litellm/utils.py
+++ b/litellm/utils.py
@@ -7022,6 +7022,7 @@ 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 23c6ccf9c0a..8d0a063dab5 100644
--- a/model_prices_and_context_window.json
+++ b/model_prices_and_context_window.json
@@ -1939,6 +1939,7 @@
     "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,
@@ -2025,6 +2026,7 @@
     "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,
@@ -2111,6 +2113,7 @@
     "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,
@@ -2197,6 +2200,7 @@
     "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,
@@ -2278,6 +2282,7 @@
     "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,
@@ -2364,6 +2369,7 @@
     "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,
@@ -2760,6 +2766,7 @@
             "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,
@@ -2804,6 +2811,7 @@
             "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,
@@ -2848,6 +2856,7 @@
             "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,
@@ -2892,6 +2901,7 @@
             "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,
@@ -2936,6 +2946,7 @@
             "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,
@@ -2980,6 +2991,7 @@
             "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,
@@ -3827,6 +3839,7 @@
         "deprecation_date": "2027-07-08",
         "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",
@@ -3964,6 +3977,7 @@
             "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,
@@ -15928,6 +15942,7 @@
             "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,
@@ -16461,6 +16476,7 @@
             "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,
@@ -21268,6 +21284,7 @@
         "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,
@@ -21425,6 +21442,7 @@
         "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,
@@ -32864,6 +32882,7 @@
             "/v1/messages"
         ],
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_parallel_function_calling": true,
         "supports_reasoning": true,
@@ -32931,6 +32950,7 @@
             "/v1/messages"
         ],
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_parallel_function_calling": true,
         "supports_reasoning": true,
@@ -32974,6 +32994,7 @@
             "/v1/messages"
         ],
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_parallel_function_calling": true,
         "supports_reasoning": true,
@@ -49051,6 +49072,7 @@
         "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,
@@ -49128,6 +49150,7 @@
         "prompt_cache_min_tokens": 512,
         "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,
@@ -51528,6 +51551,7 @@
         "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,
@@ -51566,6 +51590,7 @@
         "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,
@@ -51809,6 +51834,7 @@
             "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,
@@ -59133,6 +59159,7 @@
             "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,
@@ -65209,6 +65236,7 @@
         "prompt_cache_min_tokens": 512,
         "source": "https://deepinfra.com/pricing",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
@@ -65524,6 +65552,7 @@
         "prompt_cache_min_tokens": 1024,
         "source": "https://deepinfra.com/pricing",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_function_calling": true,
         "supports_reasoning": true,
         "supports_response_schema": true,
@@ -67521,6 +67550,7 @@
         "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,
@@ -67596,6 +67626,7 @@
         "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,
@@ -67809,6 +67840,7 @@
         "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,
@@ -67874,6 +67906,7 @@
         "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,
@@ -68711,6 +68744,7 @@
         "litellm_provider": "perplexity",
         "mode": "responses",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "prompt_cache_min_tokens": 512,
         "supports_web_search": true,
         "supports_function_calling": true,
@@ -68734,6 +68768,7 @@
         "litellm_provider": "perplexity",
         "mode": "responses",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_web_search": true,
         "supports_function_calling": true,
         "input_cost_per_token": 2e-06,
@@ -70810,6 +70845,7 @@
         "supports_vision": true,
         "supports_web_search": true,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "prompt_cache_min_tokens": 512,
         "supports_sampling_params": false
     },
@@ -70830,6 +70866,7 @@
         "supports_vision": true,
         "prompt_cache_min_tokens": 1024,
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_sampling_params": false
     },
     "aihubmix/coding-glm-5.3": {
@@ -73453,6 +73490,7 @@
     "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,
@@ -73567,6 +73605,7 @@
         "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,
@@ -75054,6 +75093,7 @@
             "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,
@@ -75106,6 +75146,7 @@
             "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,
@@ -75150,6 +75191,7 @@
         "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,
@@ -75197,6 +75239,7 @@
             "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,
@@ -75233,6 +75276,7 @@
         "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,
@@ -75289,6 +75333,7 @@
             "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,
@@ -75335,6 +75380,7 @@
             "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,
@@ -75375,6 +75421,7 @@
         "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,
@@ -75416,6 +75463,7 @@
         "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,
@@ -75462,6 +75510,7 @@
             "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,
@@ -75513,6 +75562,7 @@
             "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,
@@ -75559,6 +75609,7 @@
             "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,
@@ -75586,6 +75637,7 @@
         "litellm_provider": "perplexity",
         "mode": "responses",
         "supports_adaptive_thinking": true,
+        "thinking_on_by_default": true,
         "supports_web_search": true,
         "supports_function_calling": true,
         "input_cost_per_token": 1e-07,
@@ -75616,6 +75668,7 @@
         "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,
@@ -75667,6 +75720,7 @@
             "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,
@@ -75717,6 +75771,7 @@
             "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,
@@ -75761,6 +75816,7 @@
             "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,
@@ -77516,6 +77572,7 @@
             "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,
@@ -77730,6 +77787,7 @@
             "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,
@@ -77894,6 +77952,7 @@
             "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,
@@ -78362,6 +78421,7 @@
         "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/unit/llms/anthropic/messages/native/test_anthropic_messages_effort.py b/tests/unit/llms/anthropic/messages/native/test_anthropic_messages_effort.py
index b1eed12b4a3..c31b94aacd9 100644
--- a/tests/unit/llms/anthropic/messages/native/test_anthropic_messages_effort.py
+++ b/tests/unit/llms/anthropic/messages/native/test_anthropic_messages_effort.py
@@ -363,11 +363,12 @@ CLEAR_TOOL_USES_EDIT: Final = {"type": "clear_tool_uses_20250919"}
         pytest.param("claude-sonnet-4-6", _claude_code_payload(effort="high"), True, id="adaptive-model"),
         pytest.param("claude-3-5-haiku-latest", _claude_code_payload(), False, id="non-reasoning-model"),
         pytest.param("claude-haiku-4-5", _claude_code_payload(), True, id="legacy-thinking-model"),
+        pytest.param(
+            "claude-opus-4-8", {"reasoning_effort": "none"}, False, id="adaptive-model-without-default-thinking"
+        ),
     ],
 )
 def test_clear_thinking_edit_dropped_exactly_when_thinking_is(model, params, keeps_thinking):
-    """Anthropic rejects a clear_thinking edit without thinking, so every path that drops
-    thinking must drop the edit too, and leave other edits alone"""
     result = _transform(
         model,
         {
@@ -382,10 +383,10 @@ def test_clear_thinking_edit_dropped_exactly_when_thinking_is(model, params, kee
     assert result["context_management"] == {"edits": expected_edits}
 
 
-def test_clear_thinking_edit_kept_for_always_on_thinking_model_without_thinking():
-    """An always-on model keeps thinking adaptively after reasoning_effort='none' drops the param"""
+@pytest.mark.parametrize("model", ["claude-fable-5", "claude-sonnet-5", "claude-opus-5", "claude-haiku-5-5"])
+def test_clear_thinking_edit_kept_when_model_thinks_without_thinking_param(model):
     result = _transform(
-        "claude-fable-5",
+        model,
         {"max_tokens": 8192, "reasoning_effort": "none", "context_management": {"edits": [CLEAR_THINKING_EDIT]}},
     )
 
diff --git a/tests/unit/llms/bedrock/messages/invoke_transformations/test_anthropic_claude_transformation.py b/tests/unit/llms/bedrock/messages/invoke_transformations/test_anthropic_claude_transformation.py
index cf31bdec96c..cdabb36c8d9 100644
--- a/tests/unit/llms/bedrock/messages/invoke_transformations/test_anthropic_claude_transformation.py
+++ b/tests/unit/llms/bedrock/messages/invoke_transformations/test_anthropic_claude_transformation.py
@@ -2203,8 +2203,6 @@ def test_bedrock_invoke_transform_emits_adaptive_thinking_for_opus_4_8():
     ],
 )
 def test_bedrock_invoke_keeps_thinking_for_clear_thinking_edit_when_base_drops_thinking(thinking_params):
-    """The base messages transform drops thinking for Opus 4.5 here. Bedrock keeps the
-    clear_thinking edit long enough to add the minimum enabled thinking back, then strips it"""
     from litellm.types.router import GenericLiteLLMParams
 
     result = AmazonAnthropicClaudeMessagesConfig().transform_anthropic_messages_request(
diff --git a/tests/unit/llms/bedrock_mantle/test_bedrock_mantle_messages_transformation.py b/tests/unit/llms/bedrock_mantle/test_bedrock_mantle_messages_transformation.py
index 5cca57744b0..03700c0672c 100644
--- a/tests/unit/llms/bedrock_mantle/test_bedrock_mantle_messages_transformation.py
+++ b/tests/unit/llms/bedrock_mantle/test_bedrock_mantle_messages_transformation.py
@@ -235,6 +235,13 @@ class TestRequestBody:
                 ["clear_tool_uses_20250919"],
                 id="no-thinking-support-drops-edit",
             ),
+            pytest.param(
+                "anthropic.claude-3-5-haiku-20241022-v1:0",
+                {},
+                None,
+                ["clear_thinking_20251015", "clear_tool_uses_20250919"],
+                id="caller-edit-without-thinking-forwarded",
+            ),
             pytest.param(
                 "anthropic.claude-opus-4-5-20251101-v1:0",
                 {"thinking": {"type": "adaptive"}, "output_config": {"effort": "high"}},
@@ -258,7 +265,7 @@ class TestRequestBody:
             ),
         ],
     )
-    def test_clear_thinking_edit_forwarded_only_with_thinking(
+    def test_clear_thinking_edit_dropped_only_with_dropped_thinking(
         self, model, thinking_params, expected_thinking, expected_edit_types
     ):
         body = BedrockMantleAnthropicMessagesConfig().transform_anthropic_messages_request(
diff --git a/tests/unit/test_model_prices_and_context_window.py b/tests/unit/test_model_prices_and_context_window.py
index 2aceed493a7..585ff294ffa 100644
--- a/tests/unit/test_model_prices_and_context_window.py
+++ b/tests/unit/test_model_prices_and_context_window.py
@@ -60,6 +60,7 @@ class _CopilotThinkingCapabilities(BaseModel):
     supports_adaptive_thinking: bool | None = None
     supports_legacy_thinking: bool | None = None
     thinking_always_on: bool | None = None
+    thinking_on_by_default: bool | None = None
 
 
 def _copilot_endpoint_rows(path: Path) -> Mapping[str, _CopilotEndpointRow]:
@@ -87,6 +88,7 @@ _THINKING_KEYS: Final[tuple[str, ...]] = (
     "supports_adaptive_thinking",
     "supports_legacy_thinking",
     "thinking_always_on",
+    "thinking_on_by_default",
 )
 
 
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index 665a540e462..9aaf1bf07e1 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -1205,6 +1205,7 @@ _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"},