Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the transparency burden. It discloses that the return is JSON with url and expires_at, and that free links live 30 days. It does not discuss permissions or destructive behavior, but as a creation tool, the expected behavior is clear.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.