Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations indicate readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds behavioral context by stating the calculation uses a specific formula, has no upper limit, and results are for reference only (not official). This is consistent with annotations and provides additional clarity beyond the structured hints.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.