Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish that this is a non-destructive, idempotent, non-read-only operation. The description adds useful behavioral context beyond annotations by disclosing that the operation may take up to a minute and that it returns a link to the translation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.