Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Adds real behavior beyond the annotations: sub-resources are deep-copied, the copy receives an automatic name, and the plan quota applies. Annotations only flag it as a non-idempotent, non-destructive write, so this extra context is valuable; it stops short of explaining what visibility does or what happens when the quota is hit.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.