Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds behavioral context beyond those, including the computational method (Minetti gradient cost) and the returned metrics (pace, elevation gain/loss, average grade), which helps the agent understand what happens.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.