Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Goes well beyond the annotations: discloses that the author sees the liker's identity, that only the first like fires an interaction notification, that repeat likes are silent (idempotent), that consent is required, and that unliking affects only the caller. These are non-obvious social side effects an agent must know before acting.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.