Japan Area Code MCP Server

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; import z from "zod"; import iconv from "iconv-lite"; const server = new McpServer({ name: "japan-areacode-mcp", version: "1.0.0", }); const BASE_URL = "https://www.soumu.go.jp/main_content/000323625.csv" interface AreaCodeData { kenCode: string; sityousonCode: string; tiikiCode: string; kenName: string; sityousonName1: string; sityousonName2: string; sityousonName3: string; yomigana: string; } function parseCSV(csvContent: string): AreaCodeData[] { const lines = csvContent.split("\n"); const data: AreaCodeData[] = []; for (let i = 1; i < lines.length; i++) { const line = lines[i].trim(); if (!line) continue; const columns = line.split(","); if (columns.length >= 8) { data.push({ kenCode: columns[0] || "", sityousonCode: columns[1] || "", tiikiCode: columns[2] || "", kenName: columns[3] || "", sityousonName1: columns[4] || "", sityousonName2: columns[5] || "", sityousonName3: columns[6] || "", yomigana: columns[7] || "", }); } } return data; } server.registerTool("list-areacode", { description: "List all area codes", outputSchema: z.object({ data: z.array(z.object({ kenCode: z.string(), sityousonCode: z.string(), tiikiCode: z.string(), kenName: z.string(), sityousonName1: z.string(), sityousonName2: z.string(), sityousonName3: z.string(), yomigana: z.string(), })), }), }, async () => { const csv = await fetch(BASE_URL); const arrayBuffer = await csv.arrayBuffer(); const buffer = Buffer.from(arrayBuffer); const data = iconv.decode(buffer, "shift_jis"); const structuredData = { data: parseCSV(data), }; return { content: [ { type: "text" as const, text: JSON.stringify(structuredData, null, 2), }, ], structuredContent: structuredData, }; }); server.registerTool("find-areacode", { description: "Find the area code of a given prefecture", inputSchema: z.object({ query: z.string(), }), outputSchema: z.object({ data: z.object({ kenCode: z.string(), sityousonCode: z.string(), tiikiCode: z.string(), kenName: z.string(), sityousonName1: z.string(), sityousonName2: z.string(), sityousonName3: z.string(), yomigana: z.string(), }).nullable(), }), }, async ({ query }) => { const csv = await fetch(BASE_URL); const arrayBuffer = await csv.arrayBuffer(); const buffer = Buffer.from(arrayBuffer); const data = iconv.decode(buffer, "shift_jis"); const parsedData = parseCSV(data); const areaCode = parsedData.find( (item) => item.kenName.includes(query) || item.sityousonName1.includes(query) || item.sityousonName2.includes(query) || item.sityousonName3.includes(query) || item.yomigana.includes(query) ); if (!areaCode) { return { content: [ { type: "text" as const, text: "No area code found", }, ], structuredContent: { data: null, }, }; } const structuredData = { data: areaCode, }; return { content: [ { type: "text" as const, text: JSON.stringify(structuredData, null, 2), }, ], structuredContent: structuredData, }; }); async function main() { const transport = new StdioServerTransport(); await server.connect(transport); console.error("Server started"); } main().catch((error) => { console.error(error); process.exit(1); });