Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds meaningful behavioral context beyond the annotations: it discloses the auth requirement, that the description is shown to Team members, that it becomes data-only context for agent conversations, and that an empty string clears it. This complements the destructiveHint and idempotentHint without contradicting them.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.