Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond annotations (idempotentHint=true, readOnlyHint=false), the description discloses important non-obvious behavior: the screenshot cap derives from scenario_cap, enforcement happens on keelen pushes rather than in CI, an over-cap manifest fails every push while CI stays green, and repeated identical calls change nothing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.