Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden. It discloses exactly what the tool returns (buffered rows, batches written, last flush duration) and its diagnostic purpose. It does not explicitly state 'read-only' but the status/metric nature strongly implies no side effects, which is sufficient for a status tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.