Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag readOnlyHint=false and idempotentHint=false, but the description adds a valuable behavioral guarantee: it does not autonomously repost or mass-message. This is especially useful with openWorldHint=true, clarifying the side-effect scope beyond annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.