Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the readOnly/idempotent annotations, the description adds meaningful behavioral context: proposal state versus work state, what done means, and how readyToRead should be interpreted. This is valuable nuance for a status-reading tool, though it is not exhaustive about all response semantics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.