Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish readOnly=true, destructive=false, openWorld=false, so the safety profile is covered. The description adds meaningful context beyond them: it is a lightweight call and credential values are never returned, only pass/fail, which reassures an agent about secret exposure. It stops short of saying how failures surface (error vs. fail result), keeping it at 4.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.