Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true and readOnlyHint=false, so irreversibility is largely covered by structured data. The description restates permanence and adds that it targets the 'rendered video' specifically, which is minor added value over the annotation but no information about auth requirements or side effects on assets.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.