Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent and open-world traits, but the description adds genuinely non-obvious semantics: the DaysSinceLastBan=0 ambiguity (banned today vs. never banned) and the failure contract that unresolvable ids or an unavailable upstream return an error rather than guessed data. It does not mention rate limits or any auth/key prerequisites for the upstream Steam API.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.