External API Keys Not Working Properly in Agent v0.43

Discussion
1

I’ve been testing Cursor v0.43, and while the new Agent feature is excellent, I’ve run into a serious issue with external API keys. This is something that could benefit both of us: I’d happily use my own key, pay for my subscription, and avoid burning through Cursor’s fast request limits.

But here’s the problem:

  1. OpenRouter Errors: When I try to use an external API key through OpenRouter, it throws an error saying the subscription doesn’t support it or that the key is invalid. However, the key works perfectly fine in Chat.
  2. Anthropic Issues: When using an Anthropic key, the Agent complains about a “short context window,” making it impossible to utilize properly.

Without external key support, I burned through almost my entire monthly request limit in just one day.

It’s frustrating that the Agent and Composer don’t support external keys, even when everything seems configured correctly. The situation feels strange—how can the same key work in Chat but fail in the Agent?

If this could be resolved, it would make Cursor much more flexible and user-friendly.

Any advice or fixes on this?

IMG_6204
IMG_62041207×823 111 KB

2

Hey, Composer Agent doesn’t support your API keys. You’ll need a Pro subscription to use it. However, even with a subscription, it won’t work because API keys aren’t supported.

1 Like
3

Sounds like exclusive access to a newer model with longer context, like sonnet 3.7 :slight_smile: