Need Help: "No tool output found for function call" Error After Function Call in Responses API

API
1

Hi all,

I’m working with the Responses API for my project and I’m encountering an issue after a function call.

Here’s how I’ve set up my tool definitions:

tools = [
    { "type": "web_search_preview" },
    {
        "type": "file_search",
        "vector_store_ids": ["store_id_1"],
    },
    {
        "type": "function",
        "name": "xxx",  
        "description": "xxxx",
        "strict": True,
        "parameters": {
            "type": "object",
            "properties": {},
            "required": [],
            "additionalProperties": False        
        }
    }
]

Here’s my API call logic:

api_arguments = {
    "model": self.model,
    "input": messages,
    "temperature": self.temperature
}

if tools:
    api_arguments["tools"] = tools

if previous_response_id:
    api_arguments["previous_response_id"] = previous_response_id

response = self.client.responses.create(**api_arguments)

After a function call, I am appending follow-up messages like this:

# Append the model's function call message
follow_up_messages = [output_item]

# Append the function call output
follow_up_messages.append({
    "type": "function_call_output",
    "call_id": output_item.call_id,
    "output": str(return_val)
})

logger.info(f"output_item: {output_item}")

# Request a follow-up response
follow_up_response = st.session_state.open_ai.get_llm_responses(
    follow_up_messages,
    nexi_tools, 
    None
)

The problem:
After the function call, when I try to input something new, I get this error:

*** Error occurred while question prompt: Error code: 400 - {'error': {'message': 'No tool output found for function call call_xxx.', 'type': 'invalid_request_error', 'param': 'input', 'code': None}}

It seems like the function call output isn’t being linked correctly, but I’m not sure what I’m missing.

Could someone please help me figure this out?

Thank you,
Binjan Iyer

2

I figure out the solution of the problem. I did not send back the result from function call. It does not have all the information. So, OpenAI Reponses API return error.

append only function result for follow-up response

# Append the function call output
follow_up_messages.append({
    "type": "function_call_output",
    "call_id": output_item.call_id,
    "output": str(return_val)
})

# Request a follow-up response
follow_up_response = st.session_state.open_ai.get_llm_responses(
    follow_up_messages,
    nexi_tools, 
    api_arguments["previous_response_id"]
)