Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It explains the computation steps: subtotal, tax rounded to two decimals, final total. It omits potential edge cases (e.g., negative tax rate schema-constrained) but clearly describes the core behavior. No contradictions since no annotations exist.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.