Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/non-destructive, and the description still adds real behavior: accent-insensitive matching, semantic fallback ordering, empty-query ordering, and cursor-based pagination via 'next'. The only weak spot is that it advertises a 'match: semantic' parameter that is not in the input schema, which could send the agent looking for a knob that does not exist.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.