Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the safety profile (not read-only, non-destructive, idempotent), so the bar is lower; the description still adds real context by disclosing that the move applies across all networks and that the target must be at least 15 minutes out. It doesn't say what state changes (e.g., whether approval is reset) or what errors the minimum-lead-time rule produces, which keeps it below 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.