Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only provide a title, so the description carries the full burden. It discloses the return fields but not additional behavioral details like error handling, caching, or authentication requirements. For a simple health check, this is adequate but not rich.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.