Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full disclosure burden. It does contribute two real traits - it is read-only and it sorts NO_MANDATE/NEEDS_REVIEW entries lower - but it says nothing about auth requirements, pagination, or completeness of the listing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.