Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish the tool as read-only, idempotent, and non-destructive. The description adds useful behavioral context beyond that: it scopes to 'current and past exhibitions' and describes the return payload (titles, descriptions, status), which helps the agent understand the tool's scope and output.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.