When calling pencil MCP with the auto model, it often gets stuck

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

After the Pencil plug-in is installed, the corresponding pencil mcp is called incorrectly or stuck.

Steps to Reproduce

I installed the Pencil plugin in the plugin, and then logged in with my email. After that, I followed the instructions on Pencil’s welcome page and entered the prompts. However, a bad situation occurred: after about five MCP calls, it gets stuck at the progress message ‘planning next move.’ Then the words ‘reconnecting’ appear.

Expected Behavior

I think it should be currently doing the job I have provided,but not.

Operating System

Windows 10/11

Version Information

Version: 2.4.28 (system setup)
VSCode Version: 1.105.1
Commit: f3f5cec40024283013878b50c4f9be4002e0b580
Date: 2026-02-03T00:56:18.293Z
Build Type: Stable
Release Track: Early Access
Electron: 39.2.7
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Windows_NT x64 10.0.26200

For AI issues: which model did you use?

auto

For AI issues: add Request ID with privacy disabled

8334444e-5300-432a-85a0-ceeb679cb597

Does this stop you from using Cursor

No - Cursor works, but with this issue

3

Hey, thanks for the report. This looks like a known issue with an extension host timeout that can affect MCP calls.

Try a few things:

  1. Start Cursor without extensions from the terminal:

    cursor --disable-extensions

    If it works, it’s a conflict with one of the extensions.

  2. Check Process Explorer (Ctrl + Shift + P > “Developer: Open Process Explorer”). See if there’s a stuck extensionHost.

  3. Clear the extensions cache:

    • Fully close Cursor
    • Delete this folder:
      • Windows: %APPDATA%\Cursor\CachedExtensionVSIXs
    • Start Cursor again

  4. If Pencil MCP runs as a stdio server, it might be hitting the default timeout. Try temporarily disabling Pencil MCP in settings and check if the Agent works without it.

For further debugging, I’ll need:

  • A list of all installed extensions (Ctrl + Shift + X > three dots > Show Installed Extensions)
  • Logs from the Developer Console: Ctrl + Shift + P > “Developer: Toggle Developer Tools” > Console tab (screenshot or copied errors)
  • Your mcp.json config

Can you share that info?

4

This problem is gone now, but another one has appeared, which is quite strange.

I’ll try to describe it as accurately as possible.

When calling pencilmcp, the model suddenly opens a new chat while in use, and then a few seconds later it disappears, continuing the previous task as if nothing had happened. This situation has happened many, many times during the process of using pencilmcp to develop my design drafts.

Why I meet this, please provide me some help. my added mcp include figma,mongodb and pencil-mcp.

5

Oh no, it happened again.

image
image748×788 29 KB

6

I see it’s stuck on “Reconnecting" again.

But first, about the new issue with chats suddenly opening and closing. That’s strange behavior we haven’t seen often before. To figure it out, I need the info I asked for earlier:

Diagnostics:

  1. Extensions list: Ctrl + Shift + X > three dots > Show Installed Extensions. Please send the list.
  2. Logs: Ctrl + Shift + P > “Developer: Toggle Developer Tools” > Console tab. Please take a screenshot or copy the errors, especially while the chat is opening and closing.
  3. mcp.json: please share your config for Pencil, Figma, and MongoDB.

Questions:

  • Does this happen every time you use Pencil MCP, or only sometimes?
  • Does the chat open and close during specific Pencil MCP actions, or at random times?
  • Try temporarily disabling the Figma and MongoDB MCPs in settings. Does the issue still happen with only Pencil enabled?

If you can reproduce it consistently and have clear steps, it might be a bug worth logging. But first, let’s collect the data.