# Tool call failures by GPT 5.1 High in Plan Mode

**URL:** <https://forum.cursor.com/t/tool-call-failures-by-gpt-5-1-high-in-plan-mode/145589>\
**Category:** Bug Reports\
**Created:** [December 8, 2025, 7:56pm UTC](https://forum.cursor.com/t/tool-call-failures-by-gpt-5-1-high-in-plan-mode/145589 "2025-12-08T19:56:15Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Aaron\_Suydam](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/aaron_suydam/32/82961_2.png) [@Aaron\_Suydam](https://forum.cursor.com/u/Aaron_Suydam)\
**Post date:** [December 8, 2025, 7:56pm UTC](https://forum.cursor.com/t/tool-call-failures-by-gpt-5-1-high-in-plan-mode/145589/1 "2025-12-08T19:56:15Z")

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### Where does the bug appear (feature/product)?

Cursor IDE

### Describe the Bug

I asked for a plan to implement some requirements, like normal, and it thought/explored, and created a plan. So far, so good. Then I asked it to make some changes to the plan, and it froze on the tool call. This happens repeatably.

### Steps to Reproduce

Simply create a plan and then ask it to modify it using Plan Mode.

### Expected Behavior

It should modify the existing plan no problem.

### Operating System

MacOS

### Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.1.50 (Universal)  
VSCode Version: 1.105.1  
Commit: 56f0a83df8e9eb48585fcc4858a9440db4cc7770  
Date: 2025-12-06T23:39:52.834Z  
Electron: 37.7.0  
Chromium: 138.0.7204.251  
Node.js: 22.20.0  
V8: 13.8.258.32-electron.0  
OS: Darwin arm64 25.1.0

### For AI issues: which model did you use?

GPT 5.1 High Fast

### For AI issues: add Request ID with privacy disabled

c6338539-a11f-44cb-b9c1-bec630c7f32d

### Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

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**Author:** ![deanrie](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/deanrie/32/1263_2.png) [@deanrie](https://forum.cursor.com/u/deanrie)\
**Post date:** [December 8, 2025, 8:06pm UTC](https://forum.cursor.com/t/tool-call-failures-by-gpt-5-1-high-in-plan-mode/145589/2 "2025-12-08T20:06:03Z")

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Hey, thanks for the report. This matches a known bug in the create\_plan tool during plan updates - it can hang or time out. Temporary workaround: copy the markdown of the current plan into a new agent window and continue there. See the accepted answer: [Cursor planning mode crash](https://forum.cursor.com/t/cursor-planning-mode-crash/144481)

Could you please share:

- Screenshots of errors from Help \> Toggle Developer Tools \> Console at the time of the hang
- The result of launching with extensions disabled: `cursor --disable-extensions`
- Whether it reproduces on a different model

I’ll pass this to the team. Let me know if the workaround helps.

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**Author:** ![system](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/system/32/99069_2.png) [@system](https://forum.cursor.com/u/system)\
**Post date:** [December 30, 2025, 8:06pm UTC](https://forum.cursor.com/t/tool-call-failures-by-gpt-5-1-high-in-plan-mode/145589/3 "2025-12-30T20:06:46Z")

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Closed on December 30, 2025, 8:06pm UTC

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