Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only provide a title, so the description carries the full burden. It discloses that votes are 'permanently recorded in the SHA-256 audit chain', signaling irreversibility, but does not cover other traits like authentication requirements or effects on session state.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.