Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare the write profile (readOnly=false, destructive=false, idempotent=false), and the description adds genuinely new behavior: the 10-item batch limit and the requirement to loop across multiple calls, which an agent could otherwise miss. It does not address duplicate handling or whether partial failures roll back.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.