Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (write, idempotent, destructive, open-world), so the description's added value is the async note that 'a description change may queue background rendering' and the confirmation guardrail. It does not, however, explain the destructive/overwrite nature of replacing an existing description or the meaning of destructiveHint.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.