Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=true, so safety is partly covered. The description adds genuinely new context: the refund of credits and the hard precondition that the job must not have started, which the annotations do not convey.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.