Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered; the description still adds real behavior beyond them, notably the 24-hour window (files older than that will not appear) and the fact that uploads, imports and results are all included. It does not describe pagination or what happens when the window contains more than 50 files, which is the remaining gap.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.