Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover safety (readOnly, idempotent, not destructive). Description adds that an open analysis is a policy process, not a coverage decision, which is useful context. However, it does not disclose other behaviors like rate limits or 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.