ClaudusBridge
Bring an AI coding agent inside Unreal Engine.
ClaudusBridge embeds a full coding agent — backed by Claude (Anthropic), ChatGPT/Codex (OpenAI), or Gemini (Google) — directly in the Unreal Editor, and exposes 900+ MCP tools that let that agent (or any external MCP client) actually drive the editor: Blueprints, Materials, Niagara, UMG/Widgets, Sequencer, Assets, Levels, Textures, Multi-User and more.
It is 100% local. You sign in with your own AI account through normal OAuth — no API keys, no per-token billing from the plugin. The only data that leaves your machine is whatever your chosen provider's own login and model calls send.
This documentation covers the Unreal Engine 5.8 generation of ClaudusBridge. A separate legacy build exists for Unreal Engine 5.7 (the "Neural Cortex" generation); its features differ and are documented separately.
Headline features
- Embedded agent, in-editor. A real terminal panel inside Unreal runs the bundled agent headless. Chat with it, ask it to build assets, refactor Blueprints, wire up materials, or set up a scene — without leaving the editor.
- Three providers, one plugin. Use Claude, ChatGPT/Codex, or Gemini. Sign in with the account you already have.
- 900+ MCP tools across ~65 toolsets. Generated from Unreal's own reflection system, plus native plugin toolsets for Multi-User, Assets, Levels, Images, and Chess, plus your own authorable tool libraries.
- Drive it from outside, too. The MCP server is a standard Streamable-HTTP JSON-RPC endpoint, so external MCP clients (Claude Desktop, Cursor, Windsurf, VS Code, Gemini, Codex) can connect and control the editor.
- Multi-User aware. The agent and a human can join the same Concert session as separate participants, each with their own desktop presence avatar.
- No API keys, fully local. Vendor-free agent bundle ships in the plugin; you just need a system Node install and your own provider login.
How it works
ClaudusBridge has three cooperating pieces.
1. The in-editor terminal (ClaudusCode)
The ClaudusCode editor module ships a Slate terminal panel (SClaudusCode) backed by a real PTY — ConPTY on Windows, forkpty on macOS/Linux — with a VT parser, so it behaves like a genuine terminal inside Unreal. It launches the bundled CCAG agent (a Claude Code fork that also drives ChatGPT/Codex and Gemini in the same session) headless via your system Node.js install. The agent bundle lives inside the plugin at Resources/Agent/cli.js (~32 MB) with cli-node.js as the ESM entry point — no separate agent install required.
2. The ACP drive path
For PTY-free, programmatic control, FClaudusAcpClient speaks the Agent Client Protocol (ACP) — JSON-RPC over stdio — to the same agent. It spawns node cli-node.js --acp, performs an initialize + session/new handshake, then streams agent_message_chunk text and tool_call events back to the editor. Permission modes are default, acceptEdits, bypassPermissions, and plan. You can drive it from the console:
ClaudusCode.Acp.Start
ClaudusCode.Acp.Prompt "Create a red emissive material and apply it to the selected actor"
ClaudusCode.Acp.Stop
3. The MCP server
FClaudusBridgeServer hosts an MCP endpoint over JSON-RPC 2.0 (Streamable HTTP) at:
http://127.0.0.1:3000/mcp
A health probe is available at GET /health, which returns the server status, port, and MCP path.
By default the server runs in tool-search mode: instead of registering all ~900 tools up front, it exposes three meta-tools — list_toolsets, describe_toolset, and call_tool — so a client can discover and invoke any tool on demand. Eager mode registers every tool directly if you prefer.
The tools themselves come from three sources:
| Source | What it provides |
|---|---|
Unreal reflection (UToolsetDefinition + UFUNCTION meta=(AICallable)) | ~900 tools across ~65 toolsets (Actors/World, Blueprints, Materials, Niagara, UMG, Sequencer, Assets, Levels, Textures, …) surfaced via the ToolsetRegistry / AllToolsets engine plugins |
| Native plugin toolsets | Multi-User, Asset, Level, Image, and Chess toolsets shipped in C++ |
| ToolLibrary Blueprints | Your own tools — subclass UClaudusBridgeToolLibrary and they auto-register |
Settings
UClaudusBridgeSettings controls the server:
| Setting | Purpose |
|---|---|
ServerPortNumber | TCP port (default 3000) |
ServerUrlPath | MCP path (default /mcp) |
bEnableToolSearch | Tool-search mode vs. eager registration |
bAutoStartServer | Start the server automatically with the editor |
You can also override the port at launch with -ClaudusBridgePort=N.
What you need
- Unreal Engine 5.8 (Windows, macOS, or Linux).
- A system Node.js install — used to run the embedded agent.
- Your own AI account — Claude (Anthropic), ChatGPT/Codex (OpenAI), or Gemini (Google). Sign in via normal OAuth. No API keys required.
Architecture at a glance
ClaudusBridge is built from seven C++ modules:
| Module | Type | Role |
|---|---|---|
ClaudusBridge | Runtime | Core bridge runtime |
ClaudusBridgeEngine | Runtime | Engine-side server, client config, MCP plumbing |
ClaudusBridgeEditor | Editor | Editor integration, server lifecycle, UI |
ClaudusCode | Editor | Embedded terminal, PTY, ACP client, agent launch |
ClaudusBridgeTests | UncookedOnly | Tests |
ClaudusBridgeEngineTests | UncookedOnly | Tests |
ClaudusBridgeEditorTests | Editor | Tests |
Next steps
- See the FAQ for quick answers on accounts, providers, external MCP clients, offline use, the Node requirement, and Multi-User.
- Review the MCP server and toolset reference pages to learn what the agent can do in the editor.
- Check the Multi-User page to set up agent + human collaboration in a shared Concert session.
Questions or feedback? Join the Discord or visit galidar.com.