Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, open-world, and non-destructive behavior, so the bar is lower. The description adds a meaningful access requirement (owner or platform admin only) and clarifies what data is returned (daily/weekly summary to Telegram or email, schedule, channel, contents), which is useful context beyond annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.