Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does well: it declares the operation irreversible and discloses a dry-run/preview default via confirm. It omits permission requirements and downstream effects (e.g., what happens to the user's signups or messages), which keeps it short of 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.