Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnly/idempotent/non-destructive, so the bar is lower, yet the description still adds the 50-item page cap, the owner-only authorization constraint, and a negative scope disclosure ('never manage credentials or raw Calendar access'). It omits return/pagination cursor format, keeping it from a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.