### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

When the OpenwebUI plugin [async_context_compression](https://github.com/Fu-Jie/openwebui-extensions/blob/main/plugins/filters/async-context-compression/async_context_compression.py) is enabled, message in the request payload includes extra params that are forbidden by Mistral input schema.

### Steps to Reproduce

Send a chat completion request where the request includes ` "tool_outputs_trimmed": true`, `"trimmed_by": "async_context_compression"` :

``` curl -v -X POST "https://<host>/api/chat/completions" \ -H "Authorization: Bearer <token>" \ -H "Content-Type: application/json" -d '{ "model": "mistral/mistral-large-latest", "messages": [ { "role": "user", "content": "content" }, { "role": "assistant", "content": "content", "metadata": { "tool_outputs_trimmed": true, "trimmed_by": "async_context_compression" } } ] }' ```

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