Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden. It discloses the cloning behavior, return values (confirmation, registration_id, cloned battle, deadline_at), and the no-signup/free badge consequence. It does not cover edge cases like idempotency or limits, but it is transparent about the core mechanics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.