Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses a key limitation: 'One day of values' and notes that 'history behind each number is the priced product', which tells the agent the scope and potential paywall. However, it does not explicitly mention read-only nature, auth requirements, or rate limits, leaving some gaps.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.