openai.types.responses.response_output_item.McpCall Model not Accepted by Responses API

[michael-dommett-deel]

Confirm this is an issue with the Python library and not an underlying OpenAI API

• This is an issue with the Python library

Describe the bug

When using Responses API to do an MCP call, the Response.output field will contain an openai.types.responses.response_output_item.McpCall type. This type has a status field.

When adding this same McpCall object into the input field of a new Responses call, previously there was no issue. Now, it fails with input validation:

{'error': {'message': "Unknown parameter: 'input[2].status'.", 'type': 'invalid_request_error', 'param': 'input[2].status', 'code': 'unknown_parameter'}}

The field status of McpCall is not accepted. Thats because its not in the data model for openai.types.responses.response_output_item.McpCall.

So, why is status being added to the openai.types.responses.response_output_item.McpCall output, and why previously was this ok to use and now its not. Im talking a difference between 2025/09/25 (working) and 2025/09/29 (not working)

Removing status field from the McpCall and then sending the same request does work ✅

To Reproduce

1. Do an MCP call
2. Add the MCP call response output item to the input of a second call
3. This second call will fail (see code snippet to reproduce

Code snippets

from openai import OpenAI
client = OpenAI()
input = [{"role":"user","content":"How does tiktoken work?"}]
response_tiktoken=client.responses.create(tools=[{
            "type": "mcp",
            "server_label": "gitmcp",
            "server_url": "https://gitmcp.io/openai/tiktoken",
            "allowed_tools": ["search_tiktoken_documentation", "fetch_tiktoken_documentation"],
            "require_approval": "never"
        }],
        input=input,
        model="gpt-4o-mini")

tiktoken_mcp_call_outputs = [i for i in response_tiktoken.output if i.type == "mcp_call"]
new_input = input + tiktoken_mcp_call_outputs + [{"role":"user","content":"What did your previous message say?"}]

# this will fail due to `status` in the mcp call
response_tiktoken=client.responses.create(tools=[{
            "type": "mcp",
            "server_label": "gitmcp",
            "server_url": "https://gitmcp.io/openai/tiktoken",
            "allowed_tools": ["search_tiktoken_documentation", "fetch_tiktoken_documentation"],
            "require_approval": "never"
        }],
        input=new_input,
        model="gpt-4o-mini")

OS

macOS

Python version

3.12

Library version

openai v1.109.0

[michael-dommett-deel]

likely linked to the open api spec openai/openai-openapi#488