Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, and the description adds genuinely new context: results are limited to 'published' listings, coordinates are deliberately jittered (~100m) for landlord privacy, and exact addresses are shared only after contact with consent. That privacy caveat directly shapes how an agent should present results and is not derivable from any structured field.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.