Fix Gemini API additionalProperties error (issue #2457)

Co-Authored-By: Joe Moura <joao@crewai.com>

src/crewai/llm.py

@@ -316,7 +316,19 @@ class LLM:
             messages = [{"role": "user", "content": messages}]
         formatted_messages = self._format_messages_for_provider(messages)
 
-        # --- 2) Prepare the parameters for the completion call
+        # --- 2) If using Gemini, ensure additionalProperties is not in tool schemas
+        if tools and "gemini" in self.model.lower():
+            for i, tool in enumerate(tools):
+                if (
+                    isinstance(tool, dict) 
+                    and "function" in tool 
+                    and "parameters" in tool["function"]
+                ):
+                    params = tool["function"]["parameters"]
+                    if "additionalProperties" in params:
+                        del params["additionalProperties"]
+
+        # --- 3) Prepare the parameters for the completion call
         params = {
             "model": self.model,
             "messages": formatted_messages,

src/crewai/tools/structured_tool.py

@@ -240,6 +240,26 @@ class CrewStructuredTool:
         """Get the tool's input arguments schema."""
         return self.args_schema.model_json_schema()["properties"]
         
+    def to_openai_function(self) -> dict:
+        """Convert the tool to an OpenAI function format.
+        
+        Returns:
+            dict: A dictionary in the OpenAI function format.
+        """
+        schema = self.args_schema.model_json_schema()
+        # Remove additionalProperties field to prevent Gemini API errors
+        if "additionalProperties" in schema:
+            del schema["additionalProperties"]
+        
+        return {
+            "type": "function",
+            "function": {
+                "name": self.name,
+                "description": self.description,
+                "parameters": schema
+            }
+        }
+
     def __repr__(self) -> str:
         return (
             f"CrewStructuredTool(name='{self.name}', description='{self.description}')"

tests/tools/test_structured_tool.py

@@ -25,7 +25,7 @@ def schema_class():
     return TestSchema
 
 
-class InternalCrewStructuredTool:
+class TestInternalCrewStructuredTool:
     def test_initialization(self, basic_function, schema_class):
         """Test basic initialization of CrewStructuredTool"""
         tool = CrewStructuredTool(
@@ -144,3 +144,30 @@ class InternalCrewStructuredTool:
             {"required_param": "test", "optional_param": "custom", "nullable_param": 42}
         )
         assert result == "test custom 42"
+        
+    def test_to_openai_function_no_additional_properties(self):
+        """Test that the to_openai_function method doesn't include additionalProperties."""
+        
+        class TestSchema(BaseModel):
+            test_field: str = Field(..., description="A test field")
+        
+        def test_func(test_field: str) -> str:
+            """Test function that returns the input."""
+            return f"Test function received: {test_field}"
+        
+        tool = CrewStructuredTool(
+            name="test_tool",
+            description="A test tool",
+            args_schema=TestSchema,
+            func=test_func
+        )
+        
+        function_dict = tool.to_openai_function()
+        assert "additionalProperties" not in function_dict["function"]["parameters"]
+        
+        # Verify other properties are correct
+        assert function_dict["type"] == "function"
+        assert function_dict["function"]["name"] == "test_tool"
+        assert function_dict["function"]["description"] == "A test tool"
+        assert "properties" in function_dict["function"]["parameters"]
+        assert "test_field" in function_dict["function"]["parameters"]["properties"]