Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, and non-destructive behavior, so the description does not need to repeat those. The description adds meaningful context beyond annotations by warning of the 10-Zooq-credit cost and clarifying the returned content ('author details and text'). This is useful behavioral information, though it stops short of describing any limits, pagination, or failure behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.