Emacs Lisp Generator MCP server

The Emacs MCP Server is a powerful tool that enables generating and executing Elisp code in a running Emacs process through the Model Context Protocol (MCP). It bridges AI models like Claude with your Emacs environment, allowing AI assistants to help automate tasks directly in your editor.

Features

The server provides two main tools:

• Generate Emacs Lisp Code: Creates Elisp code to accomplish specific tasks
• Execute Emacs Lisp Code: Evaluates generated Elisp in your running Emacs instance via emacsclient

Installation

Prerequisites

• Python 3.8+
• Emacs with a running server (so emacsclient can connect)
• The uv package manager for Python

Setting Up the Environment

1. Clone the repository and navigate to it:

git clone https://github.com/username/emacs-mcp-server.git
cd emacs-mcp-server

2. Install dependencies using uv:

uv sync
source .venv/bin/activate

Usage

Running in Development Mode

To test the server in the MCP inspector:

mcp dev emacs_mcp_server.py

Installing for Claude Desktop

1. Install the MCP server:

mcp install emacs_mcp_server.py

2. Edit the claude_desktop_config.json file to include your API keys and the full path to emacsclient:

"Emacs-MCP-Server": {
  "command": "/path/to/your/.local/bin/uv",
  "args": [
    "run",
    "--with",
    "mcp[cli]",
    "--with",
    "smartfunc",
    "mcp",
    "run",
    "/path/to/your/repos/emacs-mcp-server/emacs_mcp_server.py"
  ],
  "env": {
      "OPENAI_API_KEY": "sk-xxxx",
      "EMACSCLIENT": "/your/path/to/emacsclient"
  }
}

Using the Server

Once configured:

1. Start your Emacs server if not already running:

   (server-start)
   

2. Launch Claude Desktop

3. You can now ask Claude to:

   • Generate Elisp code for specific tasks
   • Execute the generated code in your running Emacs
   • Perform complex operations by combining both tools

Example Interactions

You might ask Claude:

• "Write Elisp to organize my open buffers alphabetically"
• "Create a function to insert today's date in ISO format"
• "Find and replace text across all open buffers"

Claude will generate the appropriate Elisp code and can execute it directly in your Emacs session with your permission.

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "Emacs-MCP-Server" '{"command":"uv","args":["run","--with","mcp[cli]","--with","smartfunc","mcp","run","emacs_mcp_server.py"],"env":{"OPENAI_API_KEY":"sk-xxxx","EMACSCLIENT":"/your/path/to/emacsclient"}}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "Emacs-MCP-Server": {
            "command": "uv",
            "args": [
                "run",
                "--with",
                "mcp[cli]",
                "--with",
                "smartfunc",
                "mcp",
                "run",
                "emacs_mcp_server.py"
            ],
            "env": {
                "OPENAI_API_KEY": "sk-xxxx",
                "EMACSCLIENT": "/your/path/to/emacsclient"
            }
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "Emacs-MCP-Server": {
            "command": "uv",
            "args": [
                "run",
                "--with",
                "mcp[cli]",
                "--with",
                "smartfunc",
                "mcp",
                "run",
                "emacs_mcp_server.py"
            ],
            "env": {
                "OPENAI_API_KEY": "sk-xxxx",
                "EMACSCLIENT": "/your/path/to/emacsclient"
            }
        }
    }
}

3. Restart Claude Desktop for the changes to take effect