unreal-direktor-mcp

A stdio MCP bridge for Direktor — control the Unreal Engine editor from any AI client over the Model Context Protocol.

Direktor is an in-process Unreal Editor plugin that speaks MCP over Streamable HTTP (http://127.0.0.1:13579/mcp). This bridge is the recommended way to connect — a command/stdio MCP server that works on every client, including the many that don't speak Streamable HTTP. Clients that do support a direct HTTP endpoint can skip the bridge and point at the URL instead (see below). The editor is always the source of truth: the tool list is fetched live on every request, with a disk cache used only as a fallback so the client can still start and list tools when the editor isn't running yet.

Requirements

• Node.js 18+ (uses the global fetch and AbortSignal.timeout)
• The Direktor plugin installed and enabled in a running Unreal Editor (5.0–5.8)

Usage

No install needed — run it with npx:

npx unreal-direktor-mcp

Then point your AI client's MCP config at it. Example (Claude Desktop / Cursor mcpServers):

{
  "mcpServers": {
    "direktor": {
      "command": "npx",
      "args": ["-y", "unreal-direktor-mcp"]
    }
  }
}

If your client supports a direct HTTP MCP endpoint, you can skip this package and point it at http://127.0.0.1:13579/mcp instead.

Configuration

| Env var | Default | Purpose | |---|---|---| | DIREKTOR_URL | http://127.0.0.1:13579/mcp | Full MCP endpoint of the running editor | | DIREKTOR_PORT | 13579 | Port only (used when DIREKTOR_URL is unset) | | DIREKTOR_CACHE | .direktor-tools-cache.json next to the script | Relocate the tool-list cache (e.g. when the install dir is read-only) |

How it works

The editor is the single source of truth — the cache never shadows live data.

• tools/list — fetched live from the editor on every call, so the list is never stale. The on-disk cache is consulted only when the editor is unreachable, purely so a client that starts before the editor still has a list to show.
• tools/call — forwarded to the editor every time; the cache is never consulted. Returns a clear "Unreal Editor is not running" message if it can't connect, so you can start the editor and retry without restarting your AI client.
• Self-heal — if the editor was down and later comes up, the bridge emits notifications/tools/list_changed so the client re-lists live and drops the cached view automatically.

License

MIT