Does the description explain when to use this tool, when not to, or what alternatives exist?
Gives an explicit trigger ('Call this before answering any question about the product, hardware, printing, booth setup, guest payments, or troubleshooting') plus the reason ('answer from the docs rather than from memory'). It also carves out a when-not behavior: for plans/billing pages, share the link and don't quote prices. No competing sibling exists, so no alternative needs naming.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.