Hey, the issue is that you have both Override OpenAI Base URL enabled with a third-party endpoint and an Anthropic API Key set. When Override is enabled, all requests, including Anthropic ones, get routed through that proxy in an OpenAI-compatible format instead of using the native Anthropic Messages API. That proxy most likely doesn’t support tool calling for Claude, so the Agent describes changes in text but can’t actually edit files.
Fix:
- Turn off Override OpenAI Base URL and fully clear that field.
- Leave only Anthropic API Key enabled with your key.
- Restart Cursor with a full quit using
Cmd+Q.
You only need the Anthropic API Key. Cursor will send requests directly to the Anthropic API with full tool calling support.
If you need a proxy to reach Anthropic due to regional restrictions, that proxy must support OpenAI-format tool calling for Claude models, and not all proxies do.
A similar case was discussed here: Override Anthropic Base URL automatically switches on when using Anthropic BYOK
Let me know if that worked.