Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description must carry the burden. It only says 'Calculate profit margin' without disclosing whether the result is a decimal or percentage, or any edge-case behavior (e.g., zero selling price). Behavioral traits are minimally conveyed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.