Gemini API 400 error - invalid schema fields (prefill, enumTitles, $id)

[Neelkanthsahu02]

Description

When using Gemini models, getting 400 errors due to unsupported JSON schema fields:

• prefill
• enumTitles
• $id

These fields need to be stripped from tool definitions before sending to Gemini API.

Plugins

No response

OpenSwarm version

Latest version of Openswarm App

Steps to reproduce

1. open openswarm
2. choose gemini model
3. sent any message - example " Hi "
4. you will get the same error / bug

Screenshot and/or share link

No response

Operating System

Macos26

Terminal

No response

[guozi-lab]

Hi @nicko-ai,

I'd like to work on this if no one else has picked it up.

Here's the plan:

• Where to fix – endpoint_handlers.py
  The Gemini branch already normalizes thinking config, but doesn't strip prefill, enumTitles, and $id from params_json_schema.

• How to fix – follow the same stripping pattern used in hosted_tool_compat.py.

I'll open a PR once I have a fix. Would that work for you?