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Responses API streaming response.function_call_arguments.done event missing function name #2723

@CarsonStevensAI

Description

@CarsonStevensAI

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

The name attribute for the response.function_call_arguments.done event is None so you can't figure out which function to call. I tried uninstalling and reinstalling the latest openai version and still the same problem. I tried to add multiple tools and still the same problem.

To Reproduce

TOOLS_SPEC = [
    {
        "type": "function",
        "name": "search_parts",
        "description": "Check the availability of a specific auto part based on the provided vehicle information.",
        "parameters": {
            "type": "object",
            "properties": {
                "make": {"type": "string"},
                "model": {"type": "string"},
                "year": {"type": "string"},
                "part_type": {"type": "string"}
            },
            "required": ["make", "model", "year", "part_type"],
            "additionalProperties": False,
        },
    }
]

stream = client.responses.create(
    model="gpt-5-mini",
    input=messages,
    tools=TOOLS_SPEC,
    stream=True,
    reasoning={ "effort": "low", "summary": "auto" }
)
for event in stream:
    et = getattr(event, "type", None)
    if et == "response.function_call_arguments.done":
         print("FUNC ARGS DONE:", event.model_dump())

And I see this in the output
FUNC ARGS DONE: {'arguments': '{"make":"Ford","model":"Bronco","year":"2022","part_type":"Clutch Disc"}', 'item_id': 'fc_0accd097e3ea311f00690517123e5081a0a9cf17ce3c3a2132', 'name': None, 'output_index': 1, 'sequence_number': 125, 'type': 'response.function_call_arguments.done'}

The name attribute of the event is None so there isn't a way to tell what function the model is trying to call

Code snippets

OS

Windows

Python version

Python 3.12

Library version

openai-2.6.1

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