Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, non-destructive behavior, so the bar is lower. The description adds useful behavioral context by noting that results are ids accepted by `fetch` for full content, which helps the agent chain tools correctly.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.