Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond annotations (readOnlyHint=true, destructiveHint=false), the description adds the 500-row cap, pagination via offset, and the has_more continuation flag—crucial runtime behaviors an agent must know. It also clarifies that 'where' uses exact matching. These disclosures exceed annotations and help prevent failed or oversized calls.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.