Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds valuable behavioral context beyond annotations: only edit_keyword ever counted toward the allowance, add_keywords/disable_keyword/enable_keyword never did, and this tool does not change capacity, sell a plan, or initiate payment.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.