next-ai-draw-io/packages/mcp-server

Next AI Draw.io MCP Server

MCP (Model Context Protocol) server that enables AI agents like Claude Desktop and Cursor to generate and edit draw.io diagrams with real-time browser preview.

Self-contained - includes an embedded HTTP server, no external dependencies required.

Quick Start

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["@next-ai-drawio/mcp-server@latest"]
    }
  }
}

Installation

Claude Desktop

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["@next-ai-drawio/mcp-server@latest"]
    }
  }
}

VS Code

Add to your VS Code settings (.vscode/mcp.json in workspace or user settings):

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["@next-ai-drawio/mcp-server@latest"]
    }
  }
}

Cursor

Add to Cursor MCP config (~/.cursor/mcp.json):

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["@next-ai-drawio/mcp-server@latest"]
    }
  }
}

Cline (VS Code Extension)

1. Click the MCP Servers icon in Cline's top menu bar
2. Select the Configure tab
3. Click Configure MCP Servers to edit cline_mcp_settings.json
4. Add the drawio server:

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["@next-ai-drawio/mcp-server@latest"]
    }
  }
}

Claude Code CLI

claude mcp add drawio -- npx @next-ai-drawio/mcp-server@latest

Other MCP Clients

Use the standard MCP configuration with:

• Command: npx
• Args: ["@next-ai-drawio/mcp-server@latest"]

Usage

1. Restart your MCP client after updating config
2. Ask the AI to create a diagram:

   "Create a flowchart showing user authentication with login, MFA, and session management"

3. The diagram appears in your browser in real-time!

Features

• Real-time Preview: Diagrams appear and update in your browser as the AI creates them
• Drawing Rules: The AI gets the same layout, edge and style rules as the web app, plus the shape library docs (AWS, Azure, GCP, Kubernetes, Cisco and more), so it uses real icon names instead of guessing
• Self-check: The AI can take a screenshot of the rendered diagram and fix overlapping shapes or edges that cross shapes
• Edit Support: Modify existing diagrams with natural language instructions. If any change in an edit fails, nothing is written and the AI gets the reason and the current page XML
• Your Edits Are Kept: Changes you make in the browser are read before the AI edits again. If the AI overwrites a change you were still making, your version is saved in History
• Version History: Click History at the top right of the preview page to restore one of the last 20 versions, shown as thumbnails
• Download and Export: Save as .drawio, .png, .svg, or .drawio.svg (an SVG with the diagram embedded, which draw.io can open and edit again), from the Download button or through export_diagram
• Multi-page: List, add, rename, and delete pages, and edit any page
• Auto-save: Each session's diagram is saved to ~/.next-ai-drawio/<session-id>.drawio, so it survives a restart of the MCP client
• Themes and Dark Mode: Pick a draw.io theme under Extras > Theme; the page follows the system dark mode
• Self-contained: Embedded server, works offline (except draw.io UI which loads from embed.diagrams.net by default, configurable via DRAWIO_BASE_URL)

Available Tools

Tool	Description
start_session	Opens browser with real-time diagram preview; the result includes the drawing rules
get_drawing_guide	Return the drawing rules again, for example after a long conversation was compacted
get_shape_library	Return the shapes and icon styles of a library such as aws4, azure2, or kubernetes
create_new_diagram	Create a new diagram from XML; a plain list of mxCell elements is enough
load_diagram	Load a .drawio file from disk into the session (handles compressed files)
edit_diagram	Edit diagram by ID-based operations (update/add/delete cells); all or nothing
get_diagram	Get the current diagram XML, including your edits in the browser
screenshot_diagram	Return a PNG of a page so the AI can check the rendered diagram
export_diagram	Save diagram to a .drawio, .png, .svg, or .drawio.svg file
list_pages	List every page (tab) with id, name, index, and cell count
add_page	Append a new page without touching existing ones
rename_page	Rename a page
delete_page	Delete a page (refuses to delete the last one)

Continue a Diagram Later

After every change, the diagram is saved as a normal .drawio file in ~/.next-ai-drawio/, and start_session tells the AI the file path. When you resume a conversation after restarting your MCP client (for example claude --resume), the AI calls start_session and then load_diagram with that path. You can also open the file in draw.io yourself.

The newest 50 files are kept. Set DRAWIO_DATA_DIR to use another folder, or to off to turn auto-save off.

How It Works

┌─────────────────┐     stdio      ┌─────────────────┐
│  Claude Desktop │ <───────────> │   MCP Server    │
│    (AI Agent)   │               │  (this package) │
└─────────────────┘               └────────┬────────┘
                                          │
                                 ┌────────▼────────┐
                                 │ Embedded HTTP   │
                                 │ Server (:6002)  │
                                 └────────┬────────┘
                                          │
                                 ┌────────▼────────┐
                                 │  User's Browser │
                                 │ (draw.io embed) │
                                 └─────────────────┘

1. MCP Server receives tool calls from Claude via stdio
2. Embedded HTTP Server serves the draw.io UI and handles state
3. Browser shows real-time diagram updates via polling

Configuration

Variable	Default	Description
PORT	6002	Port for the embedded HTTP server
DRAWIO_BASE_URL	https://embed.diagrams.net	Base URL for the draw.io embed. Set this to use a self-hosted draw.io instance for private deployments.
DRAWIO_DATA_DIR	~/.next-ai-drawio	Folder for the auto-saved .drawio files. Set to off to turn auto-save off.
DEBUG	unset	Set to true to log debug messages to stderr.

Private Deployment (Self-hosted draw.io)

For security-sensitive environments that require private deployment of draw.io:

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["@next-ai-drawio/mcp-server@latest"],
      "env": { 
        "DRAWIO_BASE_URL": "https://drawio.your-company.com"
      }
    }
  }
}

You can deploy your own draw.io instance using the official Docker image:

docker run -d -p 8080:8080 jgraph/drawio

Then set DRAWIO_BASE_URL=http://localhost:8080 (or your server's URL). The preview page loads nothing else from the internet, so with a local draw.io it works fully offline.

Troubleshooting

Port already in use

If port 6002 is in use, the server will automatically try the next available port (up to 6020).

Or set a custom port:

{
  "mcpServers": {
    "drawio": {
      "command": "npx",
      "args": ["@next-ai-drawio/mcp-server@latest"],
      "env": { "PORT": "6003" }
    }
  }
}

"No active session"

Call start_session first to open the browser window.

Browser not updating

Check that the browser URL has the ?mcp= query parameter. The MCP session ID connects the browser to the server.

Screenshot or PNG/SVG export times out

PNG and SVG files are rendered by draw.io in the preview tab. Browsers slow down tabs that stay in the background, so the tab may not answer in time. Bring the preview tab to the front and try again.

License

Apache-2.0