Claude-4-Sonnet returned "<no message>" and consumed 27M+ tokens without response

[user528 (採購 崴米)]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

On August 18, 2025, at 11:46 AM (UTC+8), while using the Claude-4-Sonnet model, I encountered repeated error responses showing:

Model provided invalid arguments to write tool.

This happened over 10 times in a row. Each instance consumed tokens, totaling approximately 27,361,981 tokens, but no valid response was returned.

Screenshots of the error messages and token usage are attached for your reference.

This is a critical bug that caused severe token loss and prevented me from completing my task.

Steps to Reproduce

1. Open ChatGPT with Claude-4-Sonnet selected.
2. Enter a valid prompt (in my case, about extracting a service).
3. Observe that the model replies with “” and “Model provided invalid arguments to write tool.”
4. Try resending — the same error happens again.
5. Tokens are deducted despite the failure.

Note: No plugins or custom tools were involved.

Expected Behavior

The model should return a valid message. If an internal error occurs, it should:

• Not deduct tokens.
• Clearly indicate the error to the user.
• Stop repeated failures from being charged.

Token usage should only apply to successful or meaningful responses.

Screenshots / Screen Recordings

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

版本: 1.4.5 (Universal)
認可: 1.99.3
日期: af58d92614edb1f72bdd756615d131bf8dfa5290
Electron: 2025-08-13T02:08:56.371Z (5 天前)
ElectronBuildId: 34.5.8
Chromium: undefined
Node.js: 132.0.6834.210
V8: 20.19.1
OS: 13.2.152.41-electron.0

Additional Information

This bug caused an unusually high token usage (27,361,981 tokens) with zero usable output. I’ve attached screenshots showing the error messages and token consumption record for review.

I was using Claude-4-Sonnet inside Cursor, and all responses returned “” along with the error “Model provided invalid arguments to write tool.”

This made it impossible to continue my work and caused a major disruption in productivity.

Does this stop you from using Cursor

Yes - Cursor is unusable

[condor (Condor (Tee))]

Hi @user528, thank you for your report.

Based on the information so far, we’re unable to identify the root cause of the issue. To assist you further, could you please provide a bit more detail:

• Post the Request ID for the affected session (with privacy disabled), so we can review the logs. You can find instructions here: Cursor – Getting a Request ID
• Share the Token view for the requests that failed in this way.
• Check for errors by going to Settings > Network > Run Diagnostic, and let us know if any issues are reported.
• If possible, open Help > Toggle Developer Tools > Console, and copy any error messages shown there.

The extra details will help us investigate and resolve this faster. Thank you!

[user528 (採購 崴米)]

I’m unable to retrieve the Request ID for the affected session. Please advise if there’s another way to proceed.

[condor (Condor (Tee))]

@user528 without knowing more what the task was, what agent tried to do, its hard to tell what the cause is. I will forward the <no messages> info to the team.

To be able to see what happens within the request, we need a Request ID with privacy disabled.