Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, closed-world, non-destructive semantics, so the description is free to add what annotations cannot: that results are ordered by priority ('in the order it matters') and paginated via a `next` token. That ordering claim is genuinely useful behavioral context an agent would otherwise not know.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.