Hourei
Enables searching and retrieving Japanese legal information from the e-Gov Law API, including law searches by keyword, detailed law data retrieval, and revision history tracking.
What is Hourei?
Hourei is a Model Context Protocol (MCP) server that allows AI assistants like Claude, Cursor, and VS Code to enables searching and retrieving japanese legal information from the e-gov law api, including law searches by keyword, detailed law data retrieval, and revision history tracking.
Enables searching and retrieving Japanese legal information from the e-Gov Law API, including law searches by keyword, detailed law data retrieval, and revision history tracking.
This server falls under the Search & Data Extraction category on MCPgee, the world's largest MCP server directory with 33,000+ servers.
Features
- Enables searching and retrieving Japanese legal information
Use Cases
Maintainer
Works with
Installation
NPM
npx -y hourei-mcp-serverManual Installation
npx -y hourei-mcp-serverConfiguration
Configuration Details
claude_desktop_config.json
Performance
Response Metrics
Resource Usage
How to Set Up and Use Hourei
The Hourei MCP server connects AI assistants to Japan's official e-Gov Law API (e-Gov 法令 API), enabling keyword-based searches across the entire corpus of Japanese national legislation, retrieval of full law text by law number, and access to amendment revision histories. It returns structured data with hierarchical law sections, making it a practical tool for lawyers, researchers, compliance teams, and developers working with Japanese legal information. Because it queries the official government database directly, the content is authoritative and kept current with legislative changes.
Prerequisites
- Node.js 18 or higher with npx available in your PATH
- An MCP-compatible client such as Claude Desktop, Cursor, or Manus
- No API key is required — the e-Gov Law API is publicly accessible
- Basic familiarity with Japanese law naming conventions (law numbers use Japanese era names)
Install via npx (no global install required)
The server can be run directly with npx without a separate installation step. This command is used both for testing and as the launch command in your MCP client config.
npx -y hourei-mcp-serverAdd the server to Claude Desktop
Open or create the Claude Desktop configuration file at ~/Library/Application Support/Claude/claude_desktop_config.json on macOS, then add the server block below.
Restart Claude Desktop
Save the configuration file and restart Claude Desktop to load the new MCP server. No environment variables are needed since the e-Gov API requires no authentication.
Test with a keyword search
Verify the server is working by asking Claude to search for a well-known Japanese law using a Japanese keyword.
Hourei Examples
Client configuration
Add this block to your Claude Desktop configuration file at ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows).
{
"mcpServers": {
"hourei": {
"command": "npx",
"args": ["-y", "hourei-mcp-server"]
}
}
}Prompts to try
Use these prompts with Claude to search and retrieve Japanese legal information through the e-Gov Law API.
- "Search for Japanese laws related to 個人情報保護 (personal information protection)"
- "Retrieve the full text of the Civil Code (民法) using law number 明治二十九年法律第八十九号"
- "Find all laws containing the keyword 労働 (labor) and list their names and law numbers"
- "Show the revision history for the 会社法 (Companies Act)"
- "Search for laws in category 1 (constitutional and administrative law) related to 行政手続 (administrative procedure)"Troubleshooting Hourei
npx cannot find the hourei-mcp-server package
Ensure Node.js 18+ is installed and npx is working by running npx --version. If the package is not found, try clearing the npx cache with npx clear-npx-cache and retry. You can also install globally first: npm install -g hourei-mcp-server.
Law number searches return no results or unexpected data
Japanese law numbers must be in the correct Japanese era format, for example 平成十五年法律第五十七号. Confirm the law number by first doing a keyword search (search_law) to find the correct law number, then use that exact number with get_law_data.
Claude Desktop does not list hourei as an available server
Check that the JSON in claude_desktop_config.json is valid (no trailing commas, proper nesting). On macOS, the config file is at ~/Library/Application Support/Claude/claude_desktop_config.json. Restart Claude Desktop completely after editing the file.
Frequently Asked Questions about Hourei
What is Hourei?
Hourei is a Model Context Protocol (MCP) server that enables searching and retrieving japanese legal information from the e-gov law api, including law searches by keyword, detailed law data retrieval, and revision history tracking. It connects AI assistants to external tools and data sources through a standardized interface.
How do I install Hourei?
Install via npm with the command: npx -y hourei-mcp-server. Then add the server configuration to your AI client's JSON config file (e.g., claude_desktop_config.json or .cursor/mcp.json).
Which AI clients work with Hourei?
Hourei works with all major MCP-compatible AI clients including Claude Desktop, Claude Code, Cursor, VS Code (GitHub Copilot), Windsurf, and Cline.
Is Hourei free to use?
Yes, Hourei is open source and available under the MIT License license. You can use it freely in both personal and commercial projects.
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Quick Config Preview
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