Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds a genuinely useful behavioral fact beyond the annotations: the roughly 12-hour data window. It says nothing about auth requirements, rate limits, or behavior for an unknown username, so it adds value but not richly.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.