Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and reach profile is covered. The description adds the useful scope facts that results span active and expired sign-ups and are limited to the authenticated user's own creations, but says nothing about volume, ordering, or pagination for a potentially large 'ALL' listing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.