Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and openWorldHint, but the description adds meaningful context beyond those: it specifies the exact data returned (per-monitor status, uptime, incidents last 30d) and the auth requirement (no API key). This is additional transparency beyond what annotations provide.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.