Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Goes well beyond idempotentHint/destructiveHint by disclosing real consequences: 'off' still measures but never posts, 'preview' records without sending, nudges never DM under 'public', and human-approval in Slack is required regardless of posture. It also clarifies there are no per-capability settings, which prevents an agent from assuming granular override behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.