Geojp MCP server

geojp-mcp

日本語版 README はこちら

An MCP (Model Context Protocol) server that exposes two Japan-specific geodata APIs as tools for AI agents (Claude Code, Claude Desktop, and other MCP clients):

• ChibanJP — coordinates → chiban (地番, the official cadastral lot number recorded at Japan's Legal Affairs Bureau). Chiban rarely maps predictably to a residential address (住居表示) and is not exposed by most general-purpose geocoders.
• ReverseGeoJP — coordinates ⇄ Japanese address (reverse geocoding / forward geocoding).

Why chiban?

Japan uses two independent addressing systems: the residential address (住居表示) that appears on maps and mail, and the chiban — the cadastral lot number used in property registries, land transactions, and legal documents. The two do not follow a predictable pattern, so converting between them requires a dedicated lookup against registry map data, not a lookup table.

Chiban matters for real estate due diligence, land transaction platforms, and any workflow that touches Japan's registry system — a growing need as foreign investment in Japanese real estate rises. Most global geocoding APIs do not source chiban directly from registry map data, which is why this exists as a standalone tool.

Tools

All tools share a single API key. Get one at reversegeojp.com.

Two ways to run it

The tool definitions live in src/tools.ts and are shared by both entry points:

• Local (stdio) — src/index.ts. Your MCP client launches it as a child process on your machine. One user, one API key.
• Remote (HTTP, Cloudflare Workers) — src/worker.ts. Already deployed at https://mcp.reversegeojp.com; anyone can connect with their own API key, no build step required.

Setup (local/stdio)

npm install -g geojp-mcp

or, from source:

npm install
npm run build

The server reads the API key from the GEOJPAPIKEY environment variable. You normally don't run it directly — your MCP client starts it as a subprocess (see below).

Register with Claude Code

claude mcp add --scope user geojp -e GEOJP_API_KEY=your-api-key-here -- npx geojp-mcp

--scope user makes it available across all projects on your machine (omit it to register for the current project only). Verify with claude mcp list.

Argument order matters: -e/--env accepts multiple values, so it will swallow subsequent arguments if placed before the server name. Keep the order: add, then the server name, then -e.

Or configure manually in .mcp.json / ~/.claude.json:

{
  "mcpServers": {
    "geojp": {
      "type": "stdio",
      "command": "npx",
      "args": ["geojp-mcp"],
      "env": {
        "GEOJP_API_KEY": "your-api-key-here"
      }
    }
  }
}

Register with Claude Desktop

Add the same block to the mcpServers section of claudedesktopconfig.json, then restart Claude Desktop. Four tools (reversegeocode, geocode, getparcel, lookup_location) become available.

Setup (remote/HTTP)

Connect directly to the hosted server with your own API key — no install or build required:

Shortened. The full README is on GitHub.