Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds value by disclosing the return payload (site name, version, authenticated user), which matters because no output schema exists; it stops short of saying what happens when the connection or auth fails.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.