Allert message: This model does not support tools. Please select a different model and try again

[constintan]

Describe the Bug

First of all: THANKS FOR CURSOR!

About the bug:
I began the session with the auto model, asking several questions about our codebase. Everything worked fine.

I then switched the conversation to o3 Max, uploaded a Markdown file containing code and instructions, and asked for an implementation. The model replied successfully with roughly 500 lines of valid code.
However, on my very next follow-up message, Cursor returned this error instead of an answer:
“This model does not support tools. Please select a different model and try again.”

Cursor itself keeps running, but I have to switch to Claude Sonnet 4, which does not trigger this error.

Steps to Reproduce

1. Open a new chat in Cursor with the default auto model.
2. Ask a few code-related questions (no tools used).
3. Switch the model to o3 Max.
   4.Upload a Markdown file (e.g., docs/api-overview.md) so it’s visible in the context.
   5.Request an implementation based on that file.
   Expected result: o3 Max returns code (in my case ~500 lines).
   6.Send one more follow-up prompt (e.g., request refinements).
   7.Observe the immediate error message:

Expected Behavior

After step 6, o3 Max should respond normally: just as it did in step 5: without throwing the “does not support tools” error, given that no tools are in use and MCP is disabled.

Screenshots / Screen Recordings

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.2.2
VSCode Version: 1.99.3
Commit: faa03b17cce93e8a80b7d62d57f5eda6bb6ab9f0
Date: 2025-07-07T06:08:52.104Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.5.0

Additional Information

Prompt in the screenshot:
Don’t use any tools.

1. I type a string into the input — nothing happens.
2. The tests are missing, as we agreed.

[Xernive]

o3 is going under maintenance or isn’t working right now.

[constintan]

I’m not sure if that’s the issue, in the neighboring chat o3 max - works without any problems

[Illuminationx]

I’m having similar issues, my cursor AI agent isn’t able to do even basic functions. It started speaking in Greek to itself, then it started trying to analyze the Greek, and went on to type all \n\n\n\n\n\n. Another attempt it wrote out every detail it could about the webapp without ever doing anything. I’m having issues using Claude 4 Sonnet, so I think you are right to say that its not o3 that is the issue.

Likely something is going on with the cursor backend, since this same version of Cursor has been working fine all week, and I haven’t updated anything.

[deanrie]

Hey, this should be fixed. Let me know if the problem persists.

[constintan]

this doesn’t look like my case, I didn’t have any language related issues or

\n\n\n\n

My issue is related to changing the model during the session, and refusing to continue working after using the auto model in the session

[Illuminationx]

It’s fixed on my end. Thank you. When I was having issues my agent sometimes would just refuse to continue, start a couple tasks but get nowhere, without any language issues or \n\n\n\n.