build123d-mcp vs 21st.dev Magic MCP

A side-by-side comparison of two Design & Media servers — tools, transport, auth, maintenance, and copy-paste config for each.

	build123d-mcp Exposes build123d CAD operations as MCP tools so AI assistants can build, inspect, and iterate on 3D geometry interactively. Unverified stdio (local) No auth Python	21st.dev Magic MCP Generate beautiful, modern UI components from natural-language descriptions inside your IDE. Unverified stdio (local) API key TypeScript
Category	Design & Media	Design & Media
Language	Python	TypeScript
Transport	stdio (local)	stdio (local)
Auth	None	API key
GitHub stars	25	5.2k
Last commit	2 days ago	4 months ago
Verified
Actively maintained
Install	`pip install build123d-mcp`	`npx @21st-dev/cli@latest install <client> --api-key <key>`
Repo	Open	Open

Verdict

Pick build123d-mcp if you want zero-setup with no API key, and you need the broadest set of tools.

Pick 21st.dev Magic MCP if you want the official, vendor-maintained server, and you prefer the more popular, battle-tested option.

Add build123d-mcp

Install / run

pip install build123d-mcp

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "build123d-mcp": {
      "command": "uv",
      "args": [
        "tool",
        "run",
        "--python",
        "3.12",
        "build123d-mcp@latest"
      ]
    }
  }
}

Add 21st.dev Magic MCP

Install / run

npx @21st-dev/cli@latest install <client> --api-key <key>

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "21st-dev-magic-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@21st-dev/magic@latest",
        "API_KEY=\"your-api-key\""
      ]
    }
  }
}

FAQ

build123d-mcp or 21st.dev Magic MCP — which is better?

Pick build123d-mcp if you want zero-setup with no API key, and you need the broadest set of tools. Pick 21st.dev Magic MCP if you want the official, vendor-maintained server, and you prefer the more popular, battle-tested option.

Can I use both build123d-mcp and 21st.dev Magic MCP?

Yes — MCP clients let you enable multiple servers at once. Add both configs to your client's mcpServers and use whichever tool fits the task.

Do build123d-mcp and 21st.dev Magic MCP work with Claude, Cursor and Windsurf?

Both do. Copy the per-client config below into Claude Desktop, Cursor, or Windsurf.

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