fix(vertex_ai): drop unsupported output_config parameter from all requests

Vertex AI does not support the output_config parameter in its API.
This parameter is being added by Anthropic/Gemini transformations but needs
to be removed before sending requests to Vertex AI endpoints.

This fix addresses the "Extra inputs are not permitted" error (issue #22312)
when using Claude models with structured outputs on Vertex AI.

Changes:
- Drop output_config in Gemini model transformation
- Drop output_config in Anthropic partner model transformation
- Drop output_config in Anthropic experimental pass-through transformation
- Add comprehensive tests to verify output_config is dropped

Fixes: #22312
Made-with: Cursor

litellm/llms/vertex_ai/gemini/transformation.py

@@ -595,6 +595,8 @@ def _transform_request_body(
         safety_settings: Optional[List[SafetSettingsConfig]] = optional_params.pop(
             "safety_settings", None
         )  # type: ignore
+        # Drop output_config as it's not supported by Vertex AI
+        optional_params.pop("output_config", None)
         config_fields = GenerationConfig.__annotations__.keys()
 
         # If the LiteLLM client sends Gemini-supported parameter "labels", add it

litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/experimental_pass_through/transformation.py

@@ -152,4 +152,8 @@ class VertexAIPartnerModelsAnthropicMessagesConfig(AnthropicMessagesConfig, Vert
             "output_format", None
         )  # do not pass output_format in request body to vertex ai - vertex ai does not support output_format as yet
 
+        anthropic_messages_request.pop(
+            "output_config", None
+        )  # do not pass output_config in request body to vertex ai - vertex ai does not support output_config
+
         return anthropic_messages_request

litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py

@@ -107,6 +107,9 @@ class VertexAIAnthropicConfig(AnthropicConfig):
 
         # VertexAI doesn't support output_format parameter, remove it if present
         data.pop("output_format", None)
+        
+        # VertexAI doesn't support output_config parameter, remove it if present
+        data.pop("output_config", None)
 
         tools = optional_params.get("tools")
         tool_search_used = self.is_tool_search_used(tools)

tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_ai_partner_models_anthropic_transformation.py

@@ -489,3 +489,112 @@ def test_vertex_ai_partner_models_anthropic_remove_prompt_caching_scope_beta_hea
     assert (
         "anthropic-beta" not in headers2
     ), "Header should be removed if no supported values remain"
+
+
+def test_vertex_ai_anthropic_output_config_dropped():
+    """
+    Test that output_config parameter is dropped from Vertex AI Anthropic requests.
+    
+    Vertex AI does not support the output_config parameter (used for effort settings
+    in Anthropic API). This test ensures it's properly removed to prevent
+    "Extra inputs are not permitted" errors.
+    """
+    config = VertexAIAnthropicConfig()
+    
+    messages = [{"role": "user", "content": "What is 2+2?"}]
+    headers = {}
+    
+    # Simulate optional_params with output_config that would be passed in
+    optional_params = {
+        "max_tokens": 1024,
+        "output_config": {
+            "effort": "high"  # This is Anthropic-specific and not supported by Vertex AI
+        },
+    }
+    
+    # Call transform_request which should drop output_config
+    result = config.transform_request(
+        model="claude-3-5-sonnet-20241022",
+        messages=messages,
+        optional_params=optional_params,
+        litellm_params={},
+        headers=headers,
+    )
+    
+    # Verify output_config was removed
+    assert "output_config" not in result, \
+        "output_config should be dropped from Vertex AI Anthropic requests"
+    
+    # Verify other parameters are preserved
+    assert result["max_tokens"] == 1024, "max_tokens should be preserved"
+    assert "messages" in result, "messages should be present"
+
+
+def test_vertex_ai_anthropic_output_format_and_output_config_both_dropped():
+    """
+    Test that both output_format and output_config are dropped from Vertex AI requests.
+    
+    This ensures that even if both parameters somehow make it to the transform_request,
+    they are properly cleaned up before sending to Vertex AI.
+    """
+    config = VertexAIAnthropicConfig()
+    
+    messages = [{"role": "user", "content": "Extract structured data"}]
+    headers = {}
+    
+    optional_params = {
+        "max_tokens": 2048,
+        "output_format": {
+            "type": "json_schema",
+            "json_schema": {
+                "name": "data",
+                "schema": {"type": "object", "properties": {"result": {"type": "string"}}}
+            }
+        },
+        "output_config": {
+            "effort": "high"
+        },
+    }
+    
+    # Simulate parent class creating test_data with both parameters
+    # (as if the parent transform_request added them)
+    test_data = {
+        "model": "claude-3-5-sonnet-20241022",
+        "messages": messages,
+        "max_tokens": 2048,
+        "output_format": optional_params["output_format"],
+        "output_config": optional_params["output_config"],
+    }
+    
+    # Mock the parent transform_request to return data with both parameters
+    original_transform = config.__class__.__bases__[0].transform_request
+    
+    def mock_transform_request(self, model, messages, optional_params, litellm_params, headers):
+        return test_data.copy()
+    
+    config.__class__.__bases__[0].transform_request = mock_transform_request
+    
+    try:
+        result = config.transform_request(
+            model="claude-3-5-sonnet-20241022",
+            messages=messages,
+            optional_params=optional_params,
+            litellm_params={},
+            headers=headers,
+        )
+        
+        # Verify both were removed
+        assert "output_format" not in result, \
+            "output_format should be dropped from Vertex AI requests"
+        assert "output_config" not in result, \
+            "output_config should be dropped from Vertex AI requests"
+        
+        # Verify essential params are preserved
+        assert result["max_tokens"] == 2048, "max_tokens should be preserved"
+        assert "messages" in result, "messages should be present"
+        assert "model" not in result, "model should also be dropped for Vertex AI"
+        
+    finally:
+        # Restore original method
+        config.__class__.__bases__[0].transform_request = original_transform
+