Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, so the agent knows this is destructive. The description adds the key behavioral nuance that the media files themselves are not deleted—they are simply un-foldered. This is valuable context beyond the annotation and prevents the agent from overestimating the blast radius. It doesn't mention reversibility or permissions, but the core behavior is well disclosed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.