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 the core effect — updating the presence lease so the frontend sees the agent as alive — but does not mention lease duration, idempotency, or response behavior. Acceptable for a simple liveness ping, 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.