Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover safety (readOnlyHint=false, destructiveHint=false, idempotentHint=true), so the bar is lower, and the description adds real value on top: this is a two-phase operation where nothing is transmitted until confirmation, and the candidate is re-validated at confirmation time (state may have changed). It stops short of explaining expiry, error, or retry behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.