Yomitan MCP Server

A Model Context Protocol (MCP) server that provides AI agents with direct access to your local Yomitan dictionary databases.

Overview

This MCP server connects to the Yomitan browser extension's existing Native Messaging HTTP API (typically running on localhost:19633). It allows any MCP-compatible client (like OpenClaw, Claude Desktop, or Cursor) to perform rich dictionary lookups instantly, completely offline, and without any browser automation.

Managed by GoRakuDo.

Features (MCP Tools)

The server exposes 6 tools:

1. lookup — Search for a vocabulary word and return definitions, readings, and tags. (Optimized for AI context)
2. kanji — Search for detailed information about a single Kanji character.
3. tokenize — Parse a Japanese sentence into tokens and dictionary entries.
4. anki_discover — (New in v1.2.0) Auto-detect which Anki field markers (like {expression}, {glossary}) are valid in your specific Yomitan setup.
5. anki_fields — Generate populated Anki flashcard fields based on your Yomitan templates.
6. status — Check the connection status and version of your Yomitan backend.

Prerequisites

1. Yomitan Browser Extension installed in Chrome/Firefox.
2. Native Messaging enabled in Yomitan.
3. Yomitan API enabled in Yomitan Settings:
   • Go to Yomitan Settings -> Advanced.
   • Enable "Yomitan API" (Ensure the server URL is http://127.0.0.1:19633).
4. Node.js (v18+) installed.

Usage

You can run this MCP server directly using npx (no installation required):

npx yomitan-mcp-server

Usage with MCP Clients (Claude Desktop, Cursor, OpenClaw, etc.)

Add the following configuration to your MCP client's configuration file (e.g., mcp_config.json, claude_desktop_config.json):

{
  "mcpServers": {
    "yomitan-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "yomitan-mcp-server@latest"
      ]
    }
  }
}

Anki Integration

To use anki_fields effectively:

1. Configure your Anki Note Type and field mappings in Yomitan Settings -> Anki -> "Configure Anki card format...".
2. Use anki_discover first to see which markers (e.g., expression, reading, glossary, single-glossary-DictionaryName) are available in your setup.
3. If you encounter HTTP 500 errors, ensure you are using the correct marker names found via anki_discover.

Security & Privacy

• All lookups are performed entirely locally on your machine.
• No data is sent to external servers by this MCP server.
• The default HTTP API operates strictly on localhost.

Troubleshooting

• Connection Refused (ECONNREFUSED): Ensure the browser with Yomitan is running. Check that "Enable Yomitan API" is turned on in the extension's Advanced Settings.
• HTTP 500 Errors in anki_fields: This usually means a marker name is invalid or not mapped. Run anki_discover to verify your available markers.
• Insufficient Permissions: Ensure the Native Messaging component is correctly installed for your browser. You can test this within the Yomitan Settings page under "API".

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Built by GoRakuDo. Licensed under Mozilla Public License Version 2.0.