Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds rich behavioral context beyond the readOnlyHint: it explains that in_flight merges a live-ops registry with queued/running jobs, recent contains last completed charged ops, each row has a human-readable message, and it even mentions the SSE feed. It also discloses error conditions like unauthorized and rate_limited.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.