Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With only a title annotation, the description carries the disclosure burden and does useful work: it reveals the return payload (api_key, welcome package) and the critical one-time-secret behavior ("Save the api_key — it is only shown once"). It does not state authentication requirements, rate limits, or failure modes for duplicate handle/name.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.