This is a browser-based demo tool, not a production MCP server. Tools are registered via navigator.modelContext (WebMCP extension API), not standard MCP protocol. Tool definitions are present with names, descriptions, and input schemas. The server is fundamentally a client-side JavaScript demo, not a remote MCP server. Tool names follow verb_noun convention (add_to_cart, remove_from_cart, get_cart, clear_cart), which is good. Descriptions are brief but present (10-50 chars). Input schemas use enums for item_id in add_to_cart, which is excellent for constraint clarity. However, remove_from_cart lacks enum validation, and no parameter descriptions exist in any schema. Output structure is not documented. No error recovery guidance. This scores as a D-grade demo implementation.

• Add descriptions to all input schema parameters. Example: {"type":"object","properties":{"item_id":{"type":"string","description":"Menu item ID to add (espresso, latte, cold_brew, cortado, matcha, or pastry)","enum":[...]}}}
• Document output schemas for all tools. Example for get_cart: {"type":"object","properties":{"items":{"type":"array","items":{"type":"object","properties":{"id":{"type":"string"},"name":{"type":"string"},"quantity":{"type":"integer"},"price":{"type":"number"}}}},"total":{"type":"number"}}}
• Add enum constraint to remove_from_cart.inputSchema.properties.item_id to match add_to_cart: "enum":["espresso","latte","cold_brew","cortado","matcha","pastry"]
• Implement error handling with actionable messages. Example: if item_id not found, return {"error":"Invalid item_id: 'unknown'. Valid options: espresso, latte, cold_brew, cortado, matcha, pastry"}
• Convert to standard MCP protocol (HTTP or SSE transport) if this is intended as a production server. navigator.modelContext is a browser extension API, not MCP. Use mcp-server-node or similar to expose tools via standard MCP.