Excalidraw MCP Server & Agent Skill

Let your AI agent run a live Excalidraw canvas and draw diagrams. This repo provides:

• MCP Server: Connect via Model Context Protocol (Claude Desktop, Cursor, Claude Code, etc.)
• Agent Skill: Portable skill for OpenClaw agents and other skill-enabled agents

Built on top of mcp_excalidraw by @yctimlin. Added shareable links, image export, agent skill, and a hosted API.

Demo

Hosted Instance

A public instance is running at https://excalidraw-mcp.up.railway.app — no setup needed.

{
  "mcpServers": {
    "excalidraw": {
      "url": "https://excalidraw-mcp.up.railway.app/mcp"
    }
  }
}

Self-Hosting

Local

git clone https://github.com/0xArtex/excalidraw-mcp.git
cd excalidraw-mcp
npm install
npm run build
npm run canvas

Server starts at http://localhost:3000.

Docker

docker build -f Dockerfile.canvas -t excalidraw-mcp .
docker run -p 3000:3000 -e PUBLIC_URL=https://your-domain.com excalidraw-mcp

Environment Variables

| Variable | Default | Description | |----------|---------|-------------| | PORT | 3000 | Server port | | PUBLIC_URL | auto-detected | Public URL for edit links | | CANVAS_BASE_URL | http://localhost:3000 | Internal URL for renderer (auto-resolved) | | RATE_LIMIT_RPM | 10 | Rate limit per IP per minute | | MAX_ELEMENTS | 2000 | Max elements per render request | | RENDER_TIMEOUT_MS | 300000 | Render timeout (5 min) |

Configure MCP Clients

The MCP server can be connected via Streamable HTTP (hosted) or stdio (local).

Claude Desktop

Hosted:

{
  "mcpServers": {
    "excalidraw": {
      "url": "https://excalidraw-mcp.up.railway.app/mcp"
    }
  }
}

Local (node):

{
  "mcpServers": {
    "excalidraw": {
      "command": "node",
      "args": ["/path/to/excalidraw-mcp/dist/index.js"],
      "env": {
        "EXPRESS_SERVER_URL": "http://localhost:3000"
      }
    }
  }
}

Claude Code

claude mcp add excalidraw --scope user \
  -e EXPRESS_SERVER_URL=http://localhost:3000 \
  -- node /path/to/excalidraw-mcp/dist/index.js

Cursor

Config location: .cursor/mcp.json

{
  "mcpServers": {
    "excalidraw": {
      "url": "https://excalidraw-mcp.up.railway.app/mcp"
    }
  }
}

Agent Skill

For OpenClaw and other skill-enabled agents, install the skill to render diagrams with a single API call — no MCP client needed.

The skill is available at skills/excalidraw-canvas/ or can be installed from ClawhHub.

See SKILL.md for usage — it's a single curl call.

MCP Tools

| Tool | Description | |------|-------------| | start_diagram | Start a new diagram session, returns live canvas URL | | create_element | Create a shape (rectangle, ellipse, diamond, arrow, text, line) | | batch_create_elements | Create multiple elements at once | | delete_element | Remove an element | | finish_diagram | Finalize and get shareable link with image |

Development

npm run dev        # Watch + hot reload
npm run build      # Build everything
npm run type-check # TypeScript check

License

MIT

Acknowledgments

• @yctimlin - Original mcp_excalidraw project
• Excalidraw - The drawing library
• Model Context Protocol - The MCP specification