Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, open-world, idempotent, and non-destructive behavior. The description adds the default instance behavior and specifies the kind of metadata returned. This goes beyond annotations by clarifying scope and default, though it omits details like error handling or auth requirements.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.