japan-data-mcp

npm version license Japan Furigana API on x402-list

npm: @mameta/japan-data-mcp · MCP Registry: io.github.Mameta29/japan-data-mcp · transport: stdio

An MCP server that gives AI agents (Claude Desktop, Cursor, Cline, …) one-call access to the agentic-jp.com suite of Japanese data APIs. Every call is settled per-use over the x402 payment protocol — no account, no subscription, no API key.

What it covers — 28 tools across 7 APIs

API	Tools	What it does
address	`address_normalize`, `address_geocode`, `address_reverse_geocode`, `address_postal_code`, `address_parse`	Japanese address normalization, geocoding, postal-code lookup, free-form parsing
furigana	`furigana_convert`, `furigana_name_readings`, `furigana_classify`	Reading conversion, name readings, text classification
transit	`transit_station_status`, `transit_line_disruptions`, `transit_route_plan`, `transit_alternative_routes`, `transit_lines`, `transit_stations_search`	Real-time rail delays + delay-aware route planning (ODPT)
diet	`diet_member`, `diet_members_search`, `diet_minutes_search`	National Diet members and full-text proceedings search
holiday	`holiday_is_holiday`, `holiday_list`, `holiday_add_business_days`, `holiday_business_days_between`	Public holidays + business-day math
weather	`weather_forecast`, `weather_warnings`, `weather_areas`	JMA forecasts and warnings
houjin	`houjin_corporation`, `houjin_search`, `houjin_verify`, `houjin_kyb_report`	Corporate-number (法人番号) registry — 5.78M corporations, one-call KYB report

How payment works

x402 is a buyer-pays protocol. This MCP server holds your wallet and pays each API call transparently — the agent never sees a payment prompt. Calls cost roughly $0.001–$0.10 each (mostly sub-cent), settled in USDC on Base.

You fund a wallet with a small amount of USDC.
You set EVM_PRIVATE_KEY to that wallet's key.
The server pays as it goes; per-call cost is well under a cent for most tools.

Without EVM_PRIVATE_KEY the server still starts and lists every tool, but a paid tool call returns a clear "payment not configured" message — nothing is charged.

Security: the key in EVM_PRIVATE_KEY can spend that wallet's funds. Use a dedicated wallet funded with only what you intend to spend — never a primary wallet.

Setup

No install step — npx fetches and runs the server on demand.

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "japan-data": {
      "command": "npx",
      "args": ["-y", "@mameta/japan-data-mcp"],
      "env": {
        "EVM_PRIVATE_KEY": "0xYOUR_FUNDED_WALLET_KEY"
      }
    }
  }
}

Without EVM_PRIVATE_KEY the server still starts and lists all 28 tools; the paid tools then return a clear "payments disabled" error instead of running. Add a USDC-funded wallet key to enable them.

Cursor / Cline

Point the MCP client at npx -y @mameta/japan-data-mcp with the same EVM_PRIVATE_KEY env var. Transport is stdio.

From source

git clone https://github.com/Mameta29/japan-data-mcp.git
cd japan-data-mcp
npm install && npm run build
# then point the MCP client at: node /abs/path/to/dist/index.js

Example prompts

Once connected, just ask the agent in natural language:

"「東京都千代田区丸の内1-1」を正規化して緯度経度も出して" — address_normalize + address_geocode
"Is tomorrow a public holiday in Japan? If so, when is the next business day?" — holiday_is_holiday + holiday_add_business_days
"山手線いま遅れてる?渋谷から東京駅までの代替ルートは?" — transit_line_disruptions + transit_alternative_routes
"Look up the corporation with corporate number 7010401056220" — houjin_corporation
"国会で「デジタル庁」がいつどの委員会で議論されたか調べて" — diet_minutes_search

Configuration

Env var	Required	Description
`EVM_PRIVATE_KEY`	for paid tools	Private key of a USDC-funded wallet (Base / Polygon). Paid tools are disabled if absent.

Development

npm run dev        # run from source with tsx
npm run typecheck  # tsc --noEmit
npm run build      # compile to dist/

License

Apache-2.0