Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds a real content disclosure beyond the annotations — that returned data contains no SSID passwords — which tells the agent what sensitive fields will and won't be present. It stops short of describing return shape or pagination.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.