fix(bedrock): support tool search header translation for Sonnet 4.5

litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py

@@ -178,6 +178,33 @@ def _is_claude_opus_4_5(self, model: str) -> bool:
         ]
         return any(pattern in model_lower for pattern in opus_4_5_patterns)
 
+    def _supports_tool_search_on_bedrock(self, model: str) -> bool:
+        """
+        Check if the model supports tool search on Bedrock.
+
+        On Amazon Bedrock, server-side tool search is supported on Claude Opus 4.5
+        and Claude Sonnet 4.5 with the tool-search-tool-2025-10-19 beta header.
+
+        Ref: https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-search-tool
+
+        Args:
+            model: The model name
+
+        Returns:
+            True if the model supports tool search on Bedrock
+        """
+        model_lower = model.lower()
+
+        # Supported models for tool search on Bedrock
+        supported_patterns = [
+            # Opus 4.5
+            "opus-4.5", "opus_4.5", "opus-4-5", "opus_4_5",
+            # Sonnet 4.5
+            "sonnet-4.5", "sonnet_4.5", "sonnet-4-5", "sonnet_4_5",
+        ]
+
+        return any(pattern in model_lower for pattern in supported_patterns)
+
     def _filter_unsupported_beta_headers_for_bedrock(
         self, model: str, beta_set: set
     ) -> None:
@@ -186,13 +213,14 @@ def _filter_unsupported_beta_headers_for_bedrock(
 
         Extended thinking beta headers are only supported on specific Claude 4+ models.
         Advanced tool use headers are not supported on Bedrock Invoke API, but need to be
-        translated to Bedrock-specific headers for Claude Opus 4.5.
+        translated to Bedrock-specific headers for models that support tool search
+        (Claude Opus 4.5, Sonnet 4.5).
         This prevents 400 "invalid beta flag" errors on Bedrock.
 
         Note: Bedrock Invoke API fails with a 400 error when unsupported beta headers
         are sent, returning: {"message":"invalid beta flag"}
 
-        Translation for Claude Opus 4.5:
+        Translation for models supporting tool search (Opus 4.5, Sonnet 4.5):
         - advanced-tool-use-2025-11-20 -> tool-search-tool-2025-10-19 + tool-examples-2025-10-29
 
         Args:
@@ -226,10 +254,11 @@ def _filter_unsupported_beta_headers_for_bedrock(
         # Remove all filtered headers
         for beta in beta_headers_to_remove:
             beta_set.discard(beta)
-        
-        # 3. Translate advanced-tool-use to Bedrock-specific headers for Claude Opus 4.5
+
+        # 3. Translate advanced-tool-use to Bedrock-specific headers for models that support tool search
         # Ref: https://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html
-        if has_advanced_tool_use and self._is_claude_opus_4_5(model):
+        # Ref: https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-search-tool
+        if has_advanced_tool_use and self._supports_tool_search_on_bedrock(model):
             beta_set.add("tool-search-tool-2025-10-19")
             beta_set.add("tool-examples-2025-10-29")
 

tests/test_litellm/llms/bedrock/test_anthropic_beta_support.py

@@ -427,29 +427,66 @@ def test_messages_advanced_tool_use_translation_opus_4_5(self):
             "tool-examples-2025-10-29 should be added for Opus 4.5"
         )
 
-    def test_messages_advanced_tool_use_filtered_non_opus_4_5(self):
-        """Test that advanced-tool-use header is filtered out for non-Opus 4.5 models.
-
-        The translation to Bedrock-specific headers should only happen for Opus 4.5.
-        For other models, the advanced-tool-use header should just be removed.
+    def test_messages_advanced_tool_use_translation_sonnet_4_5(self):
+        """Test that advanced-tool-use header is translated to Bedrock-specific headers for Sonnet 4.5.
+
+        Regression test for: Claude Code sends advanced-tool-use-2025-11-20 header which needs
+        to be translated to tool-search-tool-2025-10-19 and tool-examples-2025-10-29 for
+        Bedrock Invoke API on Claude Sonnet 4.5.
+
+        Ref: https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-search-tool
         """
         config = AmazonAnthropicClaudeMessagesConfig()
         headers = {"anthropic-beta": "advanced-tool-use-2025-11-20"}
-
-        # Test with Sonnet 4.5 (not Opus 4.5)
+
         result = config.transform_anthropic_messages_request(
             model="us.anthropic.claude-sonnet-4-5-20250929-v1:0",
             messages=[{"role": "user", "content": "Test"}],
             anthropic_messages_optional_request_params={"max_tokens": 100},
             litellm_params={},
             headers=headers
         )
-
+
+        assert "anthropic_beta" in result
+        beta_headers = result["anthropic_beta"]
+
+        # advanced-tool-use should be removed
+        assert "advanced-tool-use-2025-11-20" not in beta_headers, (
+            "advanced-tool-use-2025-11-20 should be removed for Bedrock Invoke API"
+        )
+
+        # Bedrock-specific headers should be added for Sonnet 4.5
+        assert "tool-search-tool-2025-10-19" in beta_headers, (
+            "tool-search-tool-2025-10-19 should be added for Sonnet 4.5"
+        )
+        assert "tool-examples-2025-10-29" in beta_headers, (
+            "tool-examples-2025-10-29 should be added for Sonnet 4.5"
+        )
+
+    def test_messages_advanced_tool_use_filtered_unsupported_model(self):
+        """Test that advanced-tool-use header is filtered out for models that don't support tool search.
+
+        The translation to Bedrock-specific headers should only happen for models that
+        support tool search on Bedrock (Opus 4.5, Sonnet 4.5).
+        For other models, the advanced-tool-use header should just be removed.
+        """
+        config = AmazonAnthropicClaudeMessagesConfig()
+        headers = {"anthropic-beta": "advanced-tool-use-2025-11-20"}
+
+        # Test with Claude 3.5 Sonnet (does NOT support tool search on Bedrock)
+        result = config.transform_anthropic_messages_request(
+            model="us.anthropic.claude-3-5-sonnet-20241022-v2:0",
+            messages=[{"role": "user", "content": "Test"}],
+            anthropic_messages_optional_request_params={"max_tokens": 100},
+            litellm_params={},
+            headers=headers
+        )
+
         beta_headers = result.get("anthropic_beta", [])
-        
+
         # advanced-tool-use should be removed
         assert "advanced-tool-use-2025-11-20" not in beta_headers
-        
-        # Bedrock-specific headers should NOT be added for non-Opus 4.5
+
+        # Bedrock-specific headers should NOT be added for unsupported models
         assert "tool-search-tool-2025-10-19" not in beta_headers
         assert "tool-examples-2025-10-29" not in beta_headers