"AI Model Not Found" error when running "/summarize"

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

When attempting to run “/summarize” command while using Claude Sonnet 5.5, I get the following error…

AI Model Not Found: Invalid parameters for registry model: “claude-sonnet-5-5”

Seems to be an issue with the way 5.5 is being handled / expected.

Steps to Reproduce

  • Start a chat with Claude Sonnet 5.5 model selected.
  • Attempt to run /summarize to condense context window.

Expected Behavior

Expect chat to summarize and context window to reduce. Only get an error. Works with Claude Opus.

Operating System

MacOS

Version Information

Version: 3.27.14
VS Code Extension API: 1.128.0
Commit: 69b724ebc67ec522c1b5d287a5025f7a7e81be90
Date: 2026-10-23T21:46:59.851Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 42.11.16
Chromium: 148.0.7778.280
Node.js: 24.19.0
V8: 14.8.178.38-electron.0
xterm.js: 6.1.0-beta.291
OS: Darwin arm64 27.0.0

For AI issues: which model did you use?

Claude Sonnet 5.5

Does this stop you from using Cursor

No - Cursor works, but with this issue