Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It usefully discloses that 'Only provided fields are updated; others remain unchanged' and that it returns success or error Face, but it does not mention validation rules, permission requirements, or side effects beyond the described update.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.