A free account is all it takes: sign in with your e-mail, switch to Sandbox, and create a test API key. The sandbox is free, reads your own documents, and delivers webhooks, so the whole integration can be built and rehearsed before anything real is filed. Paste the key into Authorize below and send any request. A live key is refused from a browser on purpose: real keys belong on a server.
Works with any agent and any editor. The prompt points it at llms.txt, the skill and the OpenAPI document, tells it to build on the sandbox first, and to ask you for a key rather than invent one.