fix(gemini): forward toolConfig in image generation request body

litellm/llms/gemini/image_generation/transformation.py

@@ -148,6 +148,8 @@ class GoogleImageGenConfig(BaseImageGenerationConfig):
             }
             if tools := optional_params.get("tools"):
                 request_body["tools"] = tools
+            if tool_config := optional_params.get("toolConfig"):
+                request_body["toolConfig"] = tool_config
             return request_body
         else:
             # For other Imagen models, use the original Imagen format

litellm/llms/vertex_ai/image_generation/vertex_gemini_transformation.py

@@ -253,6 +253,8 @@ class VertexAIGeminiImageGenerationConfig(BaseImageGenerationConfig, VertexLLM):
 
         if tools := optional_params.get("tools"):
             request_body["tools"] = tools
+        if tool_config := optional_params.get("toolConfig"):
+            request_body["toolConfig"] = tool_config
 
         return request_body
 

tests/test_litellm/llms/gemini/test_gemini_image_generation_transformation.py

@@ -276,6 +276,19 @@ def test_gemini_image_generation_preserves_tool_config_side_effect():
         "retrievalConfig": {"latLng": {"latitude": 37.7, "longitude": -122.4}}
     }
 
+    request = config.transform_image_generation_request(
+        model="gemini-3.1-flash-image-preview",
+        prompt="Generate an image of a coffee shop nearby",
+        optional_params=mapped,
+        litellm_params={},
+        headers={},
+    )
+
+    assert request["tools"] == [{"googleMaps": {}}]
+    assert request["toolConfig"] == {
+        "retrievalConfig": {"latLng": {"latitude": 37.7, "longitude": -122.4}}
+    }
+
 
 def test_gemini_image_generation_usage_without_output_details_treats_output_as_image():
     config = GoogleImageGenConfig()

tests/test_litellm/llms/vertex_ai/image_generation/test_vertex_ai_image_generation_transformation.py

@@ -157,6 +157,26 @@ class TestVertexAIGeminiImageGenerationConfig:
         )
         assert request["tools"] == [{"googleSearch": {}}]
 
+    def test_transform_image_generation_request_forwards_tool_config(self):
+        """Test request transformation forwards toolConfig side-effects from tool mapping"""
+        mapped = self.config.map_openai_params(
+            {"tools": [{"googleMaps": {"latitude": 37.7, "longitude": -122.4}}]},
+            {},
+            "gemini-3.1-flash-image-preview",
+            False,
+        )
+        request = self.config.transform_image_generation_request(
+            model="gemini-3.1-flash-image-preview",
+            prompt="Generate an image of a coffee shop nearby",
+            optional_params=mapped,
+            litellm_params={},
+            headers={},
+        )
+        assert request["tools"] == [{"googleMaps": {}}]
+        assert request["toolConfig"] == {
+            "retrievalConfig": {"latLng": {"latitude": 37.7, "longitude": -122.4}}
+        }
+
     def test_transform_image_generation_request_with_candidate_count(self):
         """Test request transformation with candidate_count"""
         request = self.config.transform_image_generation_request(