Custom model "not found" for valid Anthropic model names despite verified API key

Pradeep_Tumati · July 31, 2026, 11:24am

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I added a valid, verified Anthropic API key in Settings → Models → API Keys. The key is confirmed valid and active (checked directly via the Anthropic Console, billing/credits in place). However:

No Claude models appear automatically in the model list after adding the key.
Removing and re-adding the key, and restarting Cursor, did not resolve it.
Attempting to manually add a custom model returns “no model found” for the following exact, current Anthropic model identifiers:
claude-sonnet-5
claude-opus-4-8
claude-haiku-4-5-20251001

All three are valid, currently active model names on Anthropic’s API.

Steps to Reproduce

Go to Settings → Models → API Keys
Paste a valid Anthropic API key
Confirm no visible verification indicator appears
Restart Cursor — key persists, but no Claude models show in model list
Go to Settings → Models → Add Custom Model
Enter claude-sonnet-5 (or other valid model names above)
Receive “model not found” error

Expected Behavior

I should be able to use cursor. I paid money and tool a monthly subscription… my monthly payment gets useless if I can’t use this product.
Claude models should appear in the model list once a valid Anthropic API key is added, and manually specified valid model names should be accepted.

Operating System

windows 10

Version Information

Version: 3.13.25 (user setup)
VS Code Extension API: 1.128.0
Commit: 31e8d61c448c7472e371505838a0fe34083dad50
Date: 2026-07-28T06:17:45.069Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.256

For AI issues: which model did you use?