Hey, thanks for the detailed report.
A similar issue came up recently. It turned out that the Cloud Agents API needs a separate API key. You don’t create it in the general settings. Instead, go to:
Dashboard > Cloud Agents https://cursor.com/dashboard?tab=cloud-agents > My Settings > scroll down to API Keys
Regular dashboard API keys might work for GET endpoints like /v0/models and /v0/repositories, but POST /v0/agents requires an agent-specific key. Here’s a thread with the same error: Internal error from cloud agents api
If your key is already from there, send the full curl request (without the key, of course) so I can check the payload structure. Endpoint docs: Cloud Agents API | Cursor Docs
Let me know how it goes.