Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the side-effect profile (readOnly=false, destructive=false, idempotent=false), so the bar is lower. The description adds genuinely useful context beyond that: the wishlist is created empty and privacy settings (PIN, reservations, guest items) hold safe defaults and are not configurable through this tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.