composer-mcp

Composer MCP Server

Give your AI coding agent an architecture canvas.

Design, visualize, and evolve software architecture diagrams - right from your IDE.

Composer is a visual system design tool that lets AI coding agents create and modify interactive architecture diagrams through MCP (Model Context Protocol). Your agent gets tools to add services, databases, queues, and connections, and you get a live canvas at usecomposer.com that updates in real-time.

Your IDE    MCP Server (this package)    Composer API    Your Diagram

Getting Started

Connect your IDE

Claude Code:

claude mcp add --transport http composer https://mcp.usecomposer.com

Cursor — create `.cursor/mcp.json` in your project root:

{
  "mcpServers": {
    "composer": {
      "type": "http",
      "url": "https://mcp.usecomposer.com"
    }
  }
}

Your browser will open for authorization on first use.

Claude Code

claude mcp add --transport http composer https://mcp.usecomposer.com

Cursor

Create `.cursor/mcp.json` in your project root:

{
  "mcpServers": {
    "composer": {
      "type": "http",
      "url": "https://mcp.usecomposer.com"
    }
  }
}

Codex

codex mcp add composer -- npx -y @usecomposer/mcp --stdio

VS Code (Copilot Chat)

Create `.vscode/mcp.json` in your project root:

{
  "servers": {
    "composer": {
      "type": "http",
      "url": "https://mcp.usecomposer.com"
    }
  }
}

VS Code (Cline)

Open Cline sidebar > Settings (gear icon) > MCP Servers > Add Remote Server:

{
  "mcpServers": {
    "composer": {
      "type": "http",
      "url": "https://mcp.usecomposer.com"
    }
  }
}

VS Code (Continue)

Add to `.continue/config.yaml`:

mcpServers:
  - name: composer
    url: https://mcp.usecomposer.com

Windsurf

Add to `~/.codeium/windsurf/mcp_config.json`:

{
  "mcpServers": {
    "composer": {
      "serverUrl": "https://mcp.usecomposer.com"
    }
  }
}

> Note: Windsurf uses `"serverUrl"` instead of `"url"`.

OpenCode

Create `opencode.json` in your project root:

{
  "mcp": {
    "composer": {
      "type": "remote",
      "url": "https://mcp.usecomposer.com"
    }
  }
}

Tools

Diagram Management

> Note: Call `list_diagrams` then `select_diagram` (or `create_diagram`) before using other tools.

Read

Write

Plan & Verify

Node Types

`client` · `frontend` · `backend` · `database` · `cache` · `queue` · `storage` · `external`

Edge Protocols

`REST` · `gRPC` · `GraphQL` · `WebSocket` · `TCP` · `UDP` · `async` · `event` · `internal`

Example Prompts

Once connected, try asking your AI agent:

How It Works

Authentication is handled via OAuth 2.1 — your browser opens for a one-time consent flow, and you're connected. Tool calls are proxied to the Composer API at `mcp.usecomposer.com`. Your diagram data lives on Composer's servers. The MCP server itself is stateless.

Changes made through MCP are immediately visible on the Composer canvas via real-time WebSocket sync.

Development

git clone https://github.com/olivergrabner/composer-mcp
cd composer-mcp
npm install
npm run dev        # Watch mode (rebuilds on change)
npm run build      # Production build

Links

• Composer - the visual architecture canvas
• MCP Protocol - Model Context Protocol spec
• Issues - bug reports and feature requests

License

MIT