Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds meaningful behavioral context by explaining the model is trained on historical listing asking prices, not deed-level sales, which informs the trustworthiness of the result. This is valuable context beyond the annotation flags.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.