Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only give the three hints (readOnly=false, idempotent=false, destructive=false). The description adds genuinely useful behavior beyond them: Range-based resume when possible, full re-download otherwise, the restarted=true marker, and a ~30s plugin cold-start latency. It does not explicitly warn about partial-state side effects, so not a 5, but it clearly exceeds the annotation baseline.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.