Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, non-destructive behavior, so the description's added value is the result shape and ordering: alphabetical results, 50-per-page default paging, and last-edit-time metadata. It does not discuss auth requirements or what happens on an invalid/stale cursor, which is a minor remaining gap.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.