Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive, closed-world, so safety is covered. The description adds useful context beyond that: which fields are returned, that ticket sellers are 'names only', that start/doors times appear 'when known', and that a 'last confirmed' date and data source are included, hinting at data freshness limitations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.