Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, closed-world, so the safety profile is covered. The description adds real behavioral context beyond that: alias/fuzzy matching (Mogador→Essaouira), the fact that a neighbourhood query resolves to its parent arrondissement/commune, and that results are codes rather than data.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.