CartCut

@cartesiancs/cartcut-mcp

Connects Claude, and any other MCP client, to the CartCut video editor running on your computer. Claude edits the project you have open: cutting from a transcript, adding captions, trimming and restaging clips, motion, transitions and effects. Every edit lands in CartCut's own undo history, so ⌘Z takes it back.

CartCut runs its MCP server inside the app, on http://127.0.0.1:9826/mcp. This package is the stdio side of that connection: the client starts it, and it relays every message to the app and back. It needs no configuration: it reads CartCut's token from CartCut's own settings.

Requirements

• CartCut, open. Download it here.
• Node.js 18 or later, for npx.

Install

Claude Code

claude mcp add cartcut -- npx -y @cartesiancs/cartcut-mcp

Add -s user to have it in every project. For the editing skill as well, which is what makes Claude a good editor rather than one that merely has the tools, install the plugin instead: plugins/cartcut-editing. If the skill is not installed, the bridge tells Claude where to read it.

Claude Desktop, Cursor and other clients

{
  "mcpServers": {
    "cartcut": {
      "command": "npx",
      "args": ["-y", "@cartesiancs/cartcut-mcp"]
    }
  }
}

Codex

codex mcp add cartcut -- npx -y @cartesiancs/cartcut-mcp

Configuration

Both variables are optional.

Variable	Default
CARTCUT_MCP_TOKEN	read from CartCut's settings	The token under the ⚡ icon at the bottom right of the CartCut window.
CARTCUT_MCP_URL	http://127.0.0.1:9826/mcp	Where CartCut listens.

Without CARTCUT_MCP_TOKEN, the token comes from CartCut's config.json:

• macOS: ~/Library/Application Support/cartcut-app/config.json
• Windows: %APPDATA%\cartcut-app\config.json
• Linux: ~/.config/cartcut-app/config.json

Behaviour worth knowing

CartCut can restart underneath a session. Quit it, update it, open it again: the next call opens a new session with the app and carries on, and the client is told to re-read the tool list.

A call is never sent twice. If CartCut closes while a tool call is running, the call is answered with an error rather than retried, because it may already have changed the timeline. Look at the editor before asking again.

Nothing leaves the machine. The bridge only ever talks to the address above.

Troubleshooting

• "CartCut is not running, or its MCP bridge is off": open CartCut, then reconnect (/mcp in Claude Code).
• "CartCut refused the token": CARTCUT_MCP_TOKEN is set to an old token. Unset it, or copy the current one from the ⚡ icon.
• "There is no CartCut token": CartCut has never been opened on this account. Open it once.

npx -y @cartesiancs/cartcut-mcp --version prints the version. The bridge logs to stderr and never to stdout, which carries the protocol.

License

MIT