Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds real behavioral context beyond that: the data is scoped to the current month and to received (incoming) transfers only, and it is broken into used, pending, reserved and remaining buckets — including a pending state an agent should know about.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.