Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false), but the description adds genuinely useful context beyond them: the required intentCode and a privacy guarantee that only the statement and dates are returned, never the user's e-mail, hidden limit, or other personal data. It omits behavior for unknown/expired codes, which keeps it from a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.