Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It does disclose a meaningful scope trait — results exclude private matching and automatic direct messages — which is genuinely useful. But it says nothing about permissions, whether this is a safe read-only operation, result limits/pagination, or what happens for unknown actors.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.