Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It discloses that data is historical and notes the optional list_name filter, but it does not describe return structure, sorting, pagination, or any side effects. It adds some context beyond the schema but leaves gaps.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.