Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It does disclose what data is covered (costs, tokens, code-line balance) and that it aggregates executed tasks rather than live state, which is genuinely useful. However, it says nothing about permissions, scope of the aggregation (all-time vs. per-user), or freshness, leaving gaps for an unannotated tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.