deepl-mcp-server

A Model Context Protocol (MCP) server that exposes DeepL text translation, document translation, rephrasing, and glossary and style rule lookups as MCP tools.

You need Node.js 18 or newer and a DeepL API key. Pick an API plan and create a key in your DeepL account.

The server communicates over stdio, so it is normally started by an MCP client rather than by hand. To try it directly:

DEEPL_API_KEY=your-api-key npx -y deepl-mcp-server

It exits immediately if DEEPL_API_KEY is not set.

To work on the server itself:

git clone https://github.com/DeepL/deepl-mcp-server.git
cd deepl-mcp-server
npm install

Register it as a stdio server with DEEPL_API_KEY in the server's environment. In Claude Code:

claude mcp add deepl --env DEEPL_API_KEY=your-api-key -- npx -y deepl-mcp-server

For clients configured through a JSON file:

{
  "mcpServers": {
    "deepl": {
      "command": "npx",
      "args": ["-y", "deepl-mcp-server"],
      "env": {
        "DEEPL_API_KEY": "your-api-key"
      }
    }
  }
}

Where that file lives and how each client expects local stdio servers to be declared:

• Claude Code
• Claude Desktop
• Cursor
• VS Code

To run a local checkout instead of the published package, use node as the command and the absolute path to src/index.mjs as the argument.

Notes:

• text takes either a single string or an array of strings. Each entry is translated or rephrased independently.
• Language codes are ISO 639-1, optionally with a region (en-US). Omitting sourceLangCode triggers automatic detection. A target code whose language requires a region gets a default applied: en becomes en-US, pt becomes pt-BR, zh becomes zh-Hans.
• Glossary dictionaries are keyed by non-regional codes, so get-glossary-dictionary-entries drops any region you pass.
• Translating with a glossary requires an explicit sourceLangCode.
• formality accepts less, more, default, prefer_less, and prefer_more. The prefer_* values fall back to the default when the target language has no formality support.
• translate-document reads and writes files on the machine running the server. Without outputFile, the output path is derived from the input by appending the target language code, for example report_de.pdf. With outputFormat, the derived path uses that extension instead.
• Style rules and custom instructions are read-only here. Create and edit them in your DeepL account.

MIT