From 8a38a4f76caabea0ad2184ee0e7126836a275801 Mon Sep 17 00:00:00 2001
From: rahul dhanawade <rdhanawade56@gmail.com>
Date: Wed, 18 Feb 2026 03:20:57 +0530
Subject: [PATCH] fix(vertex_ai): remove unsupported output_config/format
 params

---
 .../anthropic/transformation.py               | 14 +------
 .../test_vertex_anthropic_transformation.py   | 28 ++++++++++++++
 tests/test_vertex_anthropic_transformation.py | 38 +++++++++++++++++++
 3 files changed, 68 insertions(+), 12 deletions(-)
 create mode 100644 tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_anthropic_transformation.py
 create mode 100644 tests/test_vertex_anthropic_transformation.py

diff --git a/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py b/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py
index d9605385293..a4627949243 100644
--- a/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py
+++ b/litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/transformation.py
@@ -108,18 +108,8 @@ 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
-        if "output_config" in data:
-            output_config = data.pop("output_config")
-            if isinstance(output_config, dict):
-                # Extract the schema from Anthropic format: 
-                # {"format": {"type": "json_schema", "schema": {...}}}
-                format_obj = output_config.get("format", {})
-                if format_obj.get("type") == "json_schema":
-                    schema = format_obj.get("schema")
-                    if schema:
-                        # Map to Vertex AI's GA parameter: response_schema
-                        data["response_schema"] = schema
+        # We must remove them to avoid "Extra inputs are not permitted" errors.
+        data.pop("output_config", None)
 
         tools = optional_params.get("tools")
         tool_search_used = self.is_tool_search_used(tools)
diff --git a/tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_anthropic_transformation.py b/tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_anthropic_transformation.py
new file mode 100644
index 00000000000..fb14ffd0550
--- /dev/null
+++ b/tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/test_vertex_anthropic_transformation.py
@@ -0,0 +1,28 @@
+import pytest
+from litellm.llms.vertex_ai.vertex_ai_partner_models.anthropic.transformation import VertexAIAnthropicConfig
+
+def test_vertex_anthropic_unsupported_params_removal():
+    """
+    Test that unsupported params are removed for Claude on Vertex AI 
+    to fix Issue #21407.
+    """
+    config = VertexAIAnthropicConfig()
+    
+    messages = [{"role": "user", "content": "Hello"}]
+    optional_params = {
+        "output_config": {"effort": "high"},
+        "output_format": {"type": "json_schema"}
+    }
+    
+    transformed_data = config.transform_request(
+        model="claude-3-sonnet",
+        messages=messages,
+        optional_params=optional_params,
+        litellm_params={},
+        headers={}
+    )
+    
+    # Assertions: Verify they are GONE, not remapped
+    assert "output_config" not in transformed_data
+    assert "output_format" not in transformed_data
+    assert "response_schema" not in transformed_data
\ No newline at end of file
diff --git a/tests/test_vertex_anthropic_transformation.py b/tests/test_vertex_anthropic_transformation.py
new file mode 100644
index 00000000000..f4a9ddb737b
--- /dev/null
+++ b/tests/test_vertex_anthropic_transformation.py
@@ -0,0 +1,38 @@
+import pytest
+from litellm.llms.vertex_ai.vertex_ai_partner_models.anthropic.transformation import VertexAIAnthropicConfig
+
+def test_vertex_anthropic_output_config_transformation():
+    """
+    Test that output_config is correctly remapped to response_schema 
+    for Claude on Vertex AI to fix Issue #21407.
+    """
+    config = VertexAIAnthropicConfig()
+    
+    # 1. Setup mock Anthropic-style request data
+    messages = [{"role": "user", "content": "Generate a JSON response"}]
+    optional_params = {
+        "output_config": {
+            "format": {
+                "type": "json_schema",
+                "schema": {
+                    "type": "object",
+                    "properties": {"name": {"type": "string"}}
+                }
+            }
+        }
+    }
+    
+    # 2. Run transformation
+    transformed_data = config.transform_request(
+        model="claude-3-sonnet",
+        messages=messages,
+        optional_params=optional_params,
+        litellm_params={},
+        headers={}
+    )
+    
+    # 3. Assertions
+    assert "output_config" not in transformed_data, "output_config must be removed"
+    assert "response_schema" in transformed_data, "response_schema must be present"
+    assert transformed_data["response_schema"]["type"] == "object"
+    assert "name" in transformed_data["response_schema"]["properties"]
\ No newline at end of file