Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate readOnlyHint=true and openWorldHint=true. The description adds valuable behavioral context: hard-cached, WORM-sealed (immutable), and requires authentication. This goes beyond the annotations and helps the agent understand caching, data permanence, and 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.