Draw.io MCP server

Let's do some Vibe Diagramming with the most wide-spread diagramming tool called Draw.io (Diagrams.net).

Introduction

The Draw.io MCP server is a Model Context Protocol (MCP) implementation that brings powerful diagramming capabilities to AI agentic systems. This integration enables:

• Seamless Draw.io Integration: Connect your MCP-powered applications with Draw.io's rich diagramming functionality
• Programmatic Diagram Control: Create, modify, and manage diagram content through MCP commands
• Intelligent Diagram Analysis: Retrieve detailed information about diagrams and their components for processing by AI agents
• Agentic System Development: Build sophisticated AI workflows that incorporate visual modeling and diagram automation

As an MCP-compliant tool, it follows the standard protocol for tool integration, making it compatible with any MCP client. This implementation is particularly valuable for creating AI systems that need to:

• Generate architectural diagrams
• Visualize complex relationships
• Annotate technical documentation
• Create flowcharts and process maps programmatically

The tool supports bidirectional communication, allowing both control of Draw.io instances and extraction of diagram information for further processing by AI agents in your MCP ecosystem.

Requirements

To use the Draw.io MCP server, you'll need:

Core Components

• Node.js (v20 or higher) - Runtime environment for the MCP server
• Draw.io MCP Browser Extension - Enables communication between Draw.io and the MCP server

MCP Ecosystem

• MCP Client (e.g., MCP Inspector) - For testing and debugging the integration
• LLM with Tools Support - Any language model capable of handling MCP tool calls (e.g., GPT-4, Claude 3, etc.)

Optional for Development

• pnpm - Preferred package manager
• Chrome DevTools - For debugging when using --inspect flag

Note: The Draw.io desktop app or web version must be accessible to the system where the MCP server runs.

Configuration

WebSocket Port

The server listens on port 3333 by default for WebSocket connections from the browser extension. You can customize this port using the --extension-port or -p flag.

Default behavior (port 3333):

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["-y", "drawio-mcp-server"]
    }
  }
}

Custom port (e.g., port 8080):

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["-y", "drawio-mcp-server", "--extension-port", "8080"]
    }
  }
}

Note: When using a custom port, ensure the browser extension is configured to connect to the same port.

HTTP Transport Port

The server can expose a streamable HTTP MCP transport on port 3000. Change this using the --http-port flag:

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["-y", "drawio-mcp-server", "--transport", "http", "--http-port", "4000"]
    }
  }
}

Transport Selection

By default only the stdio transport starts. Limit or combine transports with the --transport flag:

• --transport stdio – start only stdio (CLI-friendly)
• --transport http – start only the HTTP transport (for remote clients)
• --transport stdio,http – start both transports

Running the streamable HTTP transport

Use the streamable HTTP transport when you need to reach the MCP server over the network (for example from a remote agent runtime). The Draw.io browser extension is still required, and you must opt in to the HTTP transport.

1. Start the server with HTTP enabled (optionally alongside stdio):

npx -y drawio-mcp-server --transport http --http-port 3000
# or both: npx -y drawio-mcp-server --transport stdio,http --http-port 4000

2. Verify the health endpoint:

curl http://localhost:3000/health
# { "status": "ok" }

3. Point your MCP client to the /mcp endpoint (http://localhost:3000/mcp by default). CORS is enabled for all origins so you can call it from a browser-based client as well.

Installation

Connecting with Claude Desktop

1. Install Claude Desktop

2. Open or create the configuration file:

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

3. Update it to include this server:

{
   "mcpServers":{
      "drawio":{
         "command":"npx",
         "args":[
            "-y",
            "drawio-mcp-server"
         ]
      }
   }
}

{
   "mcpServers":{
      "drawio":{
         "command":"pnpm",
         "args":[
            "dlx",
            "drawio-mcp-server"
         ]
      }
   }
}

To use a custom extension port (e.g., 8080), add "--extension-port", "8080" to the args array:

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["-y", "drawio-mcp-server", "--extension-port", "8080"]
    }
  }
}

4. Restart Claude Desktop

Connecting with oterm

This is an alternative MCP client in case you like terminal and you plan to connect to your own Ollama instance.

The configuration is usually in: ~/.local/share/oterm/config.json

{
	"mcpServers": {
		"drawio": {
			"command": "npx",
			"args": [
			  "-y",
        "drawio-mcp-server"
			]
		}
	}
}

{
	"mcpServers": {
		"drawio": {
			"command": "pnpm",
			"args": [
			  "dlx",
        "drawio-mcp-server"
			]
		}
	}
}

To use a custom extension port (e.g., 8080), add "--extension-port", "8080" to the args array:

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["-y", "drawio-mcp-server", "--extension-port", "8080"]
    }
  }
}

Connect with Zed

1. Open the Zed Preview application.
2. Click the Assistant (✨) icon in the bottom right corner.
3. Click Settings in the top right panel of the Assistant.
4. In the Context Servers section, click + Add Context Server.
5. Configure with the following:

{
  /// The name of your MCP server
  "drawio": {
    "command": {
      /// The path to the executable
      "path": "npx",
      /// The arguments to pass to the executable
      "args": ["-y","drawio-mcp-server"],
      /// The environment variables to set for the executable
      "env": {}
    }
  }
}

{
  /// The name of your MCP server
  "drawio": {
    "command": {
      /// The path to the executable
      "path": "pnpm",
      /// The arguments to pass to the executable
      "args": ["dlx","drawio-mcp-server"],
      /// The environment variables to set for the executable
      "env": {}
    }
  }
}

To use a custom extension port (e.g., 8080), add "--extension-port", "8080" to the args array:

{
  /// The name of your MCP server
  "drawio": {
    "command": {
      /// The path to the executable
      "path": "npx",
      /// The arguments to pass to the executable
      "args": ["-y","drawio-mcp-server","--extension-port","8080"],
      /// The environment variables to set for the executable
      "env": {}
    }
  }
}

Connecting with Codex

Edit the configuration usually located in: ~/.codex/config.toml

[mcp_servers.drawio]
command = "npx"
args = [
    "-y",
    "drawio-mcp-server"
]

[mcp_servers.drawio]
command = "pnpm"
args = [
    "dlx",
    "drawio-mcp-server"
]

To use a custom extension port (e.g., 8080), add "--extension-port", "8080" to the args array:

[mcp_servers.drawio]
command = "npx"
args = [
    "-y",
    "drawio-mcp-server",
    "--extension-port",
    "8080"
]

To connect to a locally running MCP with Streamable HTTP transport:

[mcp_servers.drawio]
url = "http://localhost:3000/mcp"

Browser Extension Setup

In order to control the Draw.io diagram, you need to install dedicated Browser Extension.

1. Open Draw.io in your browser
2. Install the Draw.io MCP Browser Extension from a web store or use other means