Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnly/idempotent/openWorld, and the description adds genuinely new behavioral facts: results are capped at 50 per call, ranked by votes, and 'ranks can shift between calls as votes change' (a non-determinism caveat the annotations do not capture), plus the public-only/no-contact-details boundary.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.