Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden and does well: it discloses the roster-only nature, returned user fields, sorting semantics, and pagination ritual (passing next_cursor back). It does not mention rate limits or the exact ordering of 'recent' (ascending vs. descending), but these are minor for a read-only list tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.