Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It discloses the meaningful trait that replies are moderated, and the schema adds the one-time-only constraint, but nothing is said about auth requirements, what happens after moderation, or whether the reply is publicly visible.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.