Japan Data MCP

An MCP server that gives AI agents cross-source access to Japanese public data — law, corporations, and statistics — normalized to English metadata, with source attribution on every response.

Live endpoint: https://japan-data-mcp.netlify.app/mcp (MCP over Streamable HTTP)

Most authoritative Japanese public-data APIs return Japanese-only fields, which is a barrier for non-Japanese agents and tools. This server queries the official government APIs and returns clean, English-labelled structured metadata, so an AI agent can use Japanese law/corporation/statistics data without reading Japanese.

Tools

Tool	Upstream source	API key	Status
search_japanese_law	e-Gov Law API	not required	Fully working (verified against the live API)
search_corporation	Corporate Number Web-API (National Tax Agency)	requires appId	Works with a key; without one, returns English registration guidance
search_statistics	e-Stat API (Statistics Bureau)	requires appId	Same as above

Every response carries the required source attribution and disclaimer (Government Standard Terms of Use 2.0; the Corporate Number data's no-warranty note; e-Stat's mandatory credit line).

Use it

Point any MCP client at the live endpoint. Example client config:

{
  "mcpServers": {
    "japan-data": {
      "type": "streamable-http",
      "url": "https://japan-data-mcp.netlify.app/mcp"
    }
  }
}

A plain GET /mcp returns server info and the tool list (useful for liveness checks). Tool calls use JSON-RPC 2.0 over POST /mcp (initialize → tools/list → tools/call).

Quick check (no key needed — the law tool works without one):

curl -s https://japan-data-mcp.netlify.app/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"search_japanese_law","arguments":{"keyword":"個人情報保護","limit":2}}}'

Run locally

node test/local-test.mjs

ALL PASS means the MCP initialize / tools/list / tools/call respond and the law tool returns English metadata from the real e-Gov API.

Deploy

The server is a Web-standard fetch handler (export default { fetch(request, env) }), so it runs on either platform:

• Netlify (current live deployment): a thin adapter in netlify/functions/mcp.mjs exposes it at /mcp. Deploy with netlify deploy --prod.
• Cloudflare Workers: wrangler deploy (see wrangler.toml).

The two API keys are injected as environment variables (HOJIN_APP_ID, ESTAT_APP_ID); the law tool needs no key, so the server is useful even without them. Get the keys from the Corporate Number Web-API and e-Stat API.

License

MIT