Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of disclosure. It explains the optional access_token behavior ('will use cached token if not provided'), the default limit, and the exact return structure (JSON string with id, name, audience_size, description). This goes beyond basic expectations, though it omits details about error handling or rate limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.