Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already convey read-only, idempotent, and non-destructive behavior (readOnlyHint=true, idempotentHint=true, destructiveHint=false). The description adds what the tool returns (columns, types, row count, etc.), which is useful but does not disclose additional behavioral traits beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.