Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide basic behavioral hints (not read-only, not idempotent, not destructive). The description adds only 'mutable fields', which is redundant. It does not disclose side effects, permissions, or constraints beyond what the name implies.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.