Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Goes well beyond the annotations by disclosing that content is published immediately, is labelled unverified community content, is subject to moderator review when reported, and must be self-contained without personal data. The annotations only say this is a non-read-only, non-destructive, open-world-false write; the description supplies the actual publication and moderation semantics an agent needs.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.