Hey, thanks for the report. This looks like a known pattern. There’s a similar case with Perplexity MCP: Can only use Composer 1 with Perplexity MCP server
In that case, only one mode worked (Composer 1), and specific models crashed with ERROR_OPENAI. It’s most likely related to how different chat modes initialize MCP servers.
To find the cause, could you try:
- Test in a clean profile:
cursor --user-data-dir="CursorData/Test"
Open the project, enable the MCP server, and try a specific model (for example, Claude or GPT). Does it work?
- If it works, check extensions:
- Help > Toggle Developer Tools > Console, send a request using a specific model and look for errors
- Disable extensions one by one
- Share here:
- Which exact models you tested (Claude, GPT, Gemini?)
- Your Cursor version (Menu > About Cursor > Copy)
- If you have them, errors from the Developer Console
The clean profile test result is especially important. It’ll show whether the issue is with your config or extensions, or with the MCP server itself.