Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations indicate this tool is not read-only (readOnlyHint=false) and not destructive (destructiveHint=false). The description confirms it modifies the cart and returns the updated cart. However, it does not disclose edge cases (e.g., invalid code) or additional behavioral details beyond what annotations provide.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.