Gemini Models Aren't working on Plan Mode and Agent Mode

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

The gemini models (I tested 3 Pro and 3 flash) haven’t been working for almost a week now; they only work with chat mode. Here is the error that I get:
Unable to reach the model provider
We’re having trouble connecting to the model provider. This might be temporary - please try again in a moment.
Request ID: 5448609a-9de2-4517-bc0b-2de098ec4dc3
{“error”:“ERROR_OPENAI”,“details”:{“title”:“Unable to reach the model provider”,“detail”:“We’re having trouble connecting to the model provider. This might be temporary - please try again in a moment.”,“additionalInfo”:{},“buttons”:,“planChoices”:},“isExpected”:false}

Steps to Reproduce

Just select a gemini model and select Plan mode or Agent Mode (with or without max mode)

Expected Behavior

It should call tools and start implementing changes on the codebase

Screenshots / Screen Recordings

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.2.44
VSCode Version: 1.105.1
Commit: 20adc1003928b0f1b99305dbaf845656ff81f5d0
Date: 2025-12-24T21:41:47.598Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Darwin arm64 24.5.0

For AI issues: which model did you use?

Gemini 3 Pro
Gemini 3 Flash

For AI issues: add Request ID with privacy disabled

Request ID: 9c838c6d-2f4e-4384-84b8-bc8883765423
{“error”:“ERROR_OPENAI”,“details”:{“title”:“Unable to reach the model provider”,“detail”:“We’re having trouble connecting to the model provider. This might be temporary - please try again in a moment.”,“additionalInfo”:{},“buttons”:,“planChoices”:},“isExpected”:false}

Does this stop you from using Cursor

No - Cursor works, but with this issue

Hey, thanks for the report.

This is a known issue: Gemini models can return ERROR_OPENAI in Plan/Agent Mode when MCP servers are enabled.

Please check Cursor Settings > Tools & MCP and temporarily disable all MCP servers. Then try Gemini again in a new chat.

In a similar case here: Gemini 3 Flash/Pro Not Working, this completely fixed the issue. The team is working on a fix.

Let me know if this helps.