O3 model in API often omits reasoning summary despite reasoning.summary: detailed

API
,
1

I’m experiencing an issue with the o3 model when using the new responses endpoint.

Even though I explicitly request detailed reasoning summaries with the following configuration:

"reasoning": {
  "effort": "medium",
  "summary": "detailed"
}

In most cases (more than 90% of the time), the model does not return any reasoning summary.

Here is an example of a typical response I receive:

{
    "id": "resp_bGl0ZWxsbTpjdXN0b21fbGxtX...",
    "created_at": 1751638574,
    "error": null,
    "incomplete_details": null,
    "instructions": "...",
    "metadata": {},
    "model": "o3-2025-04-16",
    "object": "response",
    "output": [
        {
            "id": "rs_6867e2304ac481a...",
            "summary": [], //<--empty reasoning summary
            "type": "reasoning",
            "encrypted_content": null,
            "status": null
        },
        {
            "arguments": {
                "query": "..."
            },
            "call_id": "call_h1pEYvnkW...",
            "name": "function_name",
            "type": "function_call",
            "id": "fc_6867e23de5e0...",
            "status": "completed"
        }
    ],
    "parallel_tool_calls": true,
    "temperature": 1,
    "tool_choice": "auto",
    "tools": [...],
    "top_p": 1,
    "max_output_tokens": null,
    "previous_response_id": null,
    "reasoning": {
        "effort": "medium",
        "summary": "detailed"
    },
    "status": "completed",
    "text": {
        "format": {
            "type": "text"
        }
    },
    "truncation": "disabled",
    "usage": {
        "input_tokens": 6661,
        "input_tokens_details": {
            "audio_tokens": null,
            "cached_tokens": 0,
            "text_tokens": null
        },
        "output_tokens": 560,
        "output_tokens_details": {
            "reasoning_tokens": 512,
            "text_tokens": null
        },
        "total_tokens": 7221
    },
    "user": null
}

So far I haven’t found a consistent workaround. Is anyone else experiencing this behavior?

Have you found any solution, or is it a known issue?

2 Likes
2

Updates on this? Facing the same issue!

1 Like
3

I am also experiencing the same issue.