Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does well by disclosing a key behavioral constraint: MCP never accepts payment or wallet keys. It also explains the intended funding mechanisms and the required Authorization Bearer format, giving useful behavioral context beyond a bare summary.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.