Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds nothing beyond the date scope: it does not say what an 'event' is, whether results can be empty, or how they are ordered or paginated. For a read tool with zero supplementary context, this is a gap.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.