Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations supplied, the description carries the full burden and does well: it declares the operation read-only, states that it writes, signs and executes nothing, and enumerates outcomes (OK, REFUSED, UNAVAILABLE) including the rule that errors and missing settings become UNAVAILABLE rather than fabricated data. It also warns that a mapping or readout is not a compliance finding. It stops short of describing pagination, size limits, or what 'the records you supply' look like.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.