jgrants-util-mcp-server

An MCP server for the public API of Jグランツ (jGrants), Japan's government subsidy portal: search subsidies, read their details, and read the text of their application guidelines.

Jグランツの公開APIを使って、補助金の検索・詳細の確認・公募要領の閲覧ができる MCP サーバーです。

Unofficial. This project is not affiliated with or endorsed by the Digital Agency (デジタル庁), which operates Jグランツ. It is written from scratch against the published API specification; it is not a fork of the Digital Agency's jgrants-mcp-server.

Tools

The server follows a skill-style layout. Its MCP instructions are one sentence saying what the tools are for and to call load_guideline first. Everything that concerns the tool set as a whole — including the conditions of use — lives in the guideline, and each tool's description covers only that tool. Agents that load many MCP servers keep only a short entry per server in their prompt, and read the guideline when they need it.

Run

Python 3.11 or later.

pip install -e .
python -m jgrants_util_mcp_server                                  # stdio, the default
jgrants-util-mcp-server --transport streamable-http --port 8000    # HTTP at /mcp

stdio is the default because a client that installed the package starts the process itself: no port, no host name, nothing to put behind a proxy. Serving it over HTTP is the deliberate case, so it is the one that has to say so.

The package declares what to run in the kari.mcp_servers entry-point group, so a client that installs the wheel can fill its own command field in — the distribution is named jgrants-util-mcp-server while the module is jgrants_util_mcp_server, and guessing one from the other is exactly the mistake that group avoids.

Behind a reverse proxy, accept the public host name as well; otherwise the server's DNS rebinding protection rejects requests whose Host is not localhost:

jgrants-util-mcp-server --transport streamable-http --host 127.0.0.1 --port 8000 \
    --allowed-host demo.mcp.gotoai.com

--host, --port and --allowed-host apply only to HTTP; given without --transport streamable-http, the server refuses to start rather than ignore them.

When bound to a non-loopback address (for example --host 0.0.0.0 on a LAN), that protection is off; restrict access with a firewall or a proxy.

In Kari

Two ways, depending on whether the server runs on the user's own machine or on a host.

As a Python package (the server runs on the user's machine). Build a wheel with python -m build --wheel, then in Kari: MCPサーバー追加 → type Python パッケージ（STDIO） → ローカル wheel ファイル → the .whl → インストール. The command field fills itself in from the entry-point group above. Kari installs it into its own bundled Python, so the user needs no Python of their own. Once it is on PyPI, the pypi.org option takes the name instead.

Over HTTP (the server runs on a host). Add a custom extension of type Streamable HTTP with the URL http://<host>:<port>/mcp, and start the server with --transport streamable-http.

Either way, give it an ASCII name such as jgrants — the name becomes part of every tool name the agent sees.

Conditions of use

These are in the guideline the agent reads; they apply to anyone presenting the results:

• Credit the source as 「出典：Jグランツ（jGrants）」.
• Treat the information as a reference; confirm the latest details on the subsidy's official page (portal_url) before applying.
• Avoid excessive repeated access to the API.

The Jグランツ API's own terms are published by the Digital Agency at https://www.jgrants-portal.go.jp/open-api; they apply to whoever runs this server.

Development

pip install -e ".[dev]"
pytest                    # offline tests
JGRANTS_LIVE=1 pytest     # also the live test against the real API
ruff check src tests

License

MIT — see LICENSE.