Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. 'List' implies a non-destructive read, which is useful, but nothing is said about failure modes (e.g., behavior when no document is open or pageIndex is out of range), return format, or whether it requires an open document. The primary behavior is disclosed; edge cases are not.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.