GPT-5.2 Responses API Broken

[round agate]

Reported by @remote mason

Bug Report: GPT-5.2 Responses API Broken

`Steps to Reproduce`

Create an agent with a system prompt.
Save said agent.

`Expected Result`

Agent responds to your input.

`Actual Result`

Unsupported parameter: 'top_p' is not supported with this model.

`Environment`

API Playground, NodeJS Application

Dec 12, 2025, 3:51 AM

Additional Information

Please provide relevant details to help resolve the issue, such as:

• ChatGPT Shared Link (if applicable).
• Screenshots or videos demonstrating the problem.

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[remote mason]

Even just saving an Agent without a prompt causes the issue.

It WILL respond if you make a change to the developer message but DO NOT save.

but as soon as you save it by clicking Update, it becomes broken again

and gpt-5.2-chat-latest doesn't work at all