MCP Server Boilerplate

Instructions

Implementation Reference

• src/maps.ts:399-454 (handler)

  The distanceMatrix function implements the core logic for the 'distance-matrix' tool using Google Maps Distance Matrix API, processes origins and destinations, formats results into markdown, and handles errors.
  export async function distanceMatrix( params: z.infer<typeof distanceMatrixSchema>, extra?: any ) { const apiKey = process.env.GOOGLE_MAPS_API_KEY; if (!apiKey) { throw new Error("GOOGLE_MAPS_API_KEY is required"); } try { const response = await googleMapsClient.distancematrix({ params: { origins: params.origins, destinations: params.destinations, mode: (params.mode || "driving") as any, key: apiKey, }, }); const rows = response.data.rows; const results = []; for (let i = 0; i < params.origins.length; i++) { for (let j = 0; j < params.destinations.length; j++) { const element = rows[i].elements[j]; results.push({ origin: params.origins[i], destination: params.destinations[j], distance: element.distance?.text || "N/A", duration: element.duration?.text || "N/A", status: element.status, }); } } return { content: [ { type: "text" as const, text: formatDistanceMatrixToMarkdown(results), }, ], }; } catch (error) { return { content: [ { type: "text" as const, text: `Error calculating distance matrix: ${ error instanceof Error ? error.message : String(error) }`, }, ], }; } }
• src/maps.ts:132-139 (schema)

  Zod schema defining the input parameters for the distance-matrix tool: origins, destinations arrays, and optional mode.
  export const distanceMatrixSchema = z.object({ origins: z.array(z.string()).describe("Array of origin locations"), destinations: z.array(z.string()).describe("Array of destination locations"), mode: z .enum(["driving", "walking", "bicycling", "transit"]) .optional() .describe("Travel mode"), });
• src/index.ts:100-107 (registration)

  Registration of the 'distance-matrix' tool on the MCP server, linking to the handler and schema.
  server.tool( "distance-matrix", "Calculate travel distance and time between multiple origins and destinations", distanceMatrixSchema.shape, async (params) => { return await distanceMatrix(params); } );
• src/maps.ts:55-66 (helper)

  Helper function to format distance matrix results into readable Markdown.
  function formatDistanceMatrixToMarkdown(results: any[]): string { let markdown = `# Distance Matrix Results\n\n`; results.forEach((result, index) => { markdown += `## ${index + 1}. ${result.origin} → ${result.destination}\n`; markdown += `Distance: ${result.distance} \n`; markdown += `Duration: ${result.duration} \n`; markdown += `Status: ${result.status} \n\n`; }); return markdown; }