[composer] ToolFormer: tool types do not match

[LiamHowe]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

When I’m using Agent, I can see there is an error that keeps showing up. This has been when using GPT-5 and Grok-code-fast-1. The error reads…
“[composer] ToolFormer: tool types do not match”
This is not stopping the agent from working but I can imagine something isn’t quite right with it.

Steps to Reproduce

Seems to happen on most responses.

Screenshots / Screen Recordings

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.7.40 (Universal)
VSCode Version: 1.99.3
Commit: df79b2380cd32922cad03529b0dc0c946c311850
Date: 2025-10-09T02:55:11.735Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.5.0

For AI issues: which model did you use?

GPT-5, Grok-code-fast-1

For AI issues: add Request ID with privacy disabled

c47029de-1697-47e4-aac3-7b00307dfd4b

Does this stop you from using Cursor

No - Cursor works, but with this issue

[deanrie]

Hey, thanks for the report. This ToolFormer type mismatch error appears to be a new issue we haven’t seen reported before.

Since it’s not blocking your work but indicates an internal validation issue with the Agent’s tool system, I’ll escalate this to the engineering team for investigation.

In the meantime, if you notice any patterns about when it occurs (specific types of requests, certain tools being used, etc.), feel free to share those details here.

[LiamHowe]

Thanks, the only thing I would says was that the model I was using at the time when I first noticed it (Grok-code-fast-1), seemed to really struggle with resolving a css issue and after 10 failed attempts, I switched to GPT-5 to see if it could resolve it - which it did first time around. The error was still showing in the new chat with GPT-5 though.

[deanrie]

Thanks for the info, that’s very helpful.

[Jack_Olmstead]

I am also just now seeing this issue:
Chip: Apple M1 Pro
Memory: 16 GB
macOS: 15.6 (24G84)

——
Version: 1.7.46
VSCode Version: 1.99.3
Commit: b9e5948c1ad20443a5cecba6b84a3c9b99d62580
Date: 2025-10-14T01:21:46.830Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.6.0

[LiamHowe]

Interesting, I’m also on M1 (but not Pro).

[Josef_Everson]

Also experiencing this issue, Macbook air, macOS: 15.1.1 (24B91)
This happens anytime it tries to create a new file and does affect functionality.

[leventov]

I think I see this error more often in the plan mode. (Cursor 1.7.53)

[deanrie]

Thanks for the info, that’s very helpful.

[Red_King]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

i get this error constantly and it makes Cursor completely unusable

[composer] ToolFormer: tool type do not match

I am on windows 11 and i have the most recent version of cursor, it does not report any issues but it is constantly stuck “creating files” but it doesnt actually do anything.

Steps to Reproduce

Simply using the Agent on this version or whatever im not even sure its just whenver i try to run it.

Expected Behavior

the agent is supposed to write code and progress through the ideas at hand

Screenshots / Screen Recordings

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.7.54 (user setup)
VSCode Version: 1.99.3
Commit: 5c17eb2968a37f66bc6662f48d6356a100b67be0
Date: 2025-10-21T19:07:38.476Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.26100

For AI issues: which model did you use?

im using the default model

Additional Information

it seems to have some kind of relevance to the “browser” function with the agent, upon disabling “browser” it sometimes would work.

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor