Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
When using Gemini 3.1 through a Google API key / BYOK, the request fails before completion. Cursor surfaces this provider error:
Provider returned error: [{ “error”: { “code”: 400, “message”: “Invalid JSON (for ‘extra_body’): no such field: ‘disable_thought_tag’”, “status”: “INVALID_ARGUMENT” } }]
This looks like Cursor is sending an extra_body field named disable_thought_tag that Google’s API rejects.
Steps to Reproduce
- Enable/use a Google API key in Cursor.
- Select Gemini 3.1 as the model.
- Send any chat or agent request.
- Observe the provider error above.
Expected Behavior
Gemini 3.1 should work when Google API key support is enabled, or Cursor should omit provider-specific request fields that Google’s API does not accept.
Operating System
MacOS
Version Information
IDE:
Version: 3.1.15
VSCode Version: 1.105.1
Commit: 3a67af7b780e0bfc8d32aefa96b8ff1cb8817f80
For AI issues: which model did you use?
Gemini 3.1 with Google API key / BYOK
For AI issues: add Request ID with privacy disabled
Not available in this report. The visible provider error is: Invalid JSON (for ‘extra_body’): no such field: ‘disable_thought_tag’.
Additional Information
Operating system reported by the machine: macOS / Darwin 25.1.0. Cursor otherwise works; this appears limited to the Gemini 3.1 + Google API key path.
Does this stop you from using Cursor
No - Cursor works, but with this issue