When attempting to set up a custom API key, Cursor displays this prompt:
Are you sure you want to enable your own ${provider} API key? Several of Cursor’s features require custom models (Tab, Apply from Chat, Composer), which cannot be billed to an API key.
The implication at this point is unclear:
- Will features that require custom models not work? OR
- Will those features work, but Cursor will still charge for them?
Proposed language if #1 is the case:
Are you sure you want to enable your own ${provider} API key? Several of Cursor’s features require our custom models (Tab, Apply from Chat, Composer), so they will be disabled.
Proposed language if #2 is the case:
Are you sure you want to enable your own ${provider} API key? Several of Cursor’s features require our custom models (Tab, Apply from Chat, Composer), and they will be billed separately from your API key.
To further clear up the confusion (see also this post), adding custom API keys should be warned against, or even disabled from the start, for Pro users. I’m saying this because after enabling my Anthropic API key, I see this:
With your Cursor Pro subscription, you do not need to use your own Anthropic key!
If I don’t need to use my own key, then why let me enter it? Warn me before.
…if it’s really true that I don’t need to enter my own API key. Because at cursor.com/settings I see this:
Enable for usage-based for premium models
“Applies to models like Sonnet 3.5 and GPT-4o beyond the monthly requests included in your plan.”
So it seems that it does make sense to enter my own Anthropic API key, even if I have a Cursor Pro subscription, in order for Cursor to not charge me for premium model usage.