Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Adds substantial context beyond the readOnly/openWorld annotations: credits cost (0.2 per successful page, including empty pages), duplicate preservation, temporary media links, and opaque cursors. These are non-obvious behavioral traits an agent needs before invoking.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.