Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds behavior beyond that: how to continue pagination (follow pagination.nextCursor into after) and that public catalog entries are excluded from results — both are non-obvious result-set facts.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.