Altar is in closed beta
Altar
Join the beta
Altar Bridge

Connect any MCP app.

Cursor, VS Code, Windsurf, Zed or any app that supports MCP can drive After Effects through Altar Bridge.

2 minmacOSAfter Effects with Altar open

Altar Bridge is a standard MCP server that runs on your Mac. Any app that can start a local (stdio) MCP server can use it. Altar installs it here:

Altar BridgeCode
~/Library/Application Support/Adobe/CEP/extensions/com.sidequestplugins.altar.cep/mcp/altar-mcp

To see it in Finder, choose Go > Go to Folder and paste the folder part of the path. The Library folder is hidden by default.

Connect

  1. Open a composition

    In After Effects, open the composition you want to work on. The check at the end reads its name.

  2. Add Altar to your app

    If your app has an AI agent that can edit its own settings, paste this into it:

    your AI app

    Add a local MCP server named altar to your MCP settings. Its command is "$HOME/Library/Application Support/Adobe/CEP/extensions/com.sidequestplugins.altar.cep/mcp/altar-mcp" with no arguments (expand $HOME to my home folder). Tell me when it is added and whether I need to restart.

    Prefer to edit the config yourself?

    Add Altar to your app’s MCP config. Replace YOUR-NAME with your Mac user name.

    Cursor (~/.cursor/mcp.json), Windsurf and most apps use mcpServers:

    mcp.jsonCode
    {
  "mcpServers": {
    "altar": {
      "command": "/Users/YOUR-NAME/Library/Application Support/Adobe/CEP/extensions/com.sidequestplugins.altar.cep/mcp/altar-mcp"
    }
  }
}

    VS Code uses servers in .vscode/mcp.json or your user MCP config:

    mcp.jsonCode
    {
  "servers": {
    "altar": {
      "type": "stdio",
      "command": "/Users/YOUR-NAME/Library/Application Support/Adobe/CEP/extensions/com.sidequestplugins.altar.cep/mcp/altar-mcp"
    }
  }
}
  3. Restart the app and check

    Restart the app or start a new chat so it loads Altar, then paste:

    your AI app

    Use Altar to tell me the title of my active composition without changing anything.

    It replies with the name of your composition. Apps outside Claude and ChatGPT / Codex aren’t checked by Altar Chat, so it doesn’t show them as connected. That’s expected.

You don’t need an API key. Your app does the thinking, on your own plan.

Try it

your AI app

Use Altar to describe my active composition and suggest one improvement. Do not change anything yet.

If it didn’t work

The app doesn’t list Altar’s tools.

Fix. Check the path for typos and that it starts with /Users/, not ~. Most apps don’t expand ~ in config files. Restart the app afterwards.

“Altar bridge not running.”

Fix. After Effects is closed or Altar’s connection stopped. Open After Effects; if it stays down, press Reconnect in Altar Chat’s Settings.

The file isn’t there.

Fix. Altar Bridge ships with Altar on macOS. Reinstall Altar from the download page, restart After Effects and try again.

More fixes on Troubleshooting.

Next