Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the bar is lower, but the description still contributes nothing: it doesn't say whether a duplicate name errors or overwrites, what happens to the ignored deprecated slug, or that the call returns the created object (output schema exists). For a non-idempotent create, side-effect details matter.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.