Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context about what the health check covers (connectivity, read-only settings, vector/age versions), which goes beyond the annotations. However, it doesn't disclose details like whether it returns a summary object or detailed diagnostics, but that's minor for a health check.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.