Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=false; the description adds that the check is scoped to 'this Mac' (local, not remote) and that the response includes remediation guidance when the check fails. That is genuine value beyond the structured fields, though it says nothing about response shape or failure modes of the check itself.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.