Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full disclosure burden. It communicates a read-only listing action, but does not disclose return format, pagination, session-state filtering, or whether it covers all sessions in the workspace. This is minimally adequate for a simple list operation but thin.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.