Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare non-read-only, open-world, non-idempotent, non-destructive behavior, so the bar is lower. The description adds genuinely new context: a cryptographic signature over 'claim:{agent_id}:{entity_id}' is required and both parties must consent, plus the important side-effect detail that the agent retains its own identity.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.