enginegate

enginegate

enginegate gives an agent a single doorway into a running Unreal Editor. Instead of a long list of editor tools, it exposes one gateway tool, unreal, with four operations: search the editor's capabilities in plain words, read one capability's contract before using it, execute a capability, and configure which capability groups are enabled.

Every call is forwarded to the editor's own local MCP endpoint, so enginegate only works while an editor with that endpoint is running. When it is not, calls come back as errors carrying the underlying connection problem — enginegate never invents an editor result.

Install

npx @reneturcios/enginegate call '{"operation":"search","query":"spawn actor"}'

Or run the container image:

docker run -i ghcr.io/cloudcorprecords/enginegate

The container defaults to the MCP server (see below). Pass CLI arguments to use it as a CLI instead.

Configuration

Environment variable	Meaning
UNREAL_MCP_URL	The editor's MCP endpoint. Default: http://127.0.0.1:3000/mcp
MCP_AUTOMATION_CAPABILITY_TOKEN	When set, sent on every forwarded call as the X-MCP-Capability-Token header.

CLI

# Search capabilities in plain words
enginegate call '{"operation":"search","query":"spawn actor"}'

# Read one internal tool's contract
enginegate call '{"operation":"describe","tool":"control_actor"}'

# Execute a capability by tool + action, or by capability id
enginegate call '{"operation":"execute","tool":"control_actor","action":"spawn","params":{"class":"PointLight"}}'
enginegate call '{"operation":"execute","capability":"control_actor.spawn","params":{"class":"PointLight"}}'

# Configure capability groups
enginegate call '{"operation":"configure","tool":"control_actor","params":{"enabled":true}}'

enginegate --version

Exit codes: 0 on success, 1 when a call fails validation or the editor cannot be reached or returns an error, 2 for usage errors.

Argument requirements are checked before anything is forwarded, and the error names the missing field:

• search requires query
• describe requires tool
• execute requires tool + action, or capability
• configure requires tool or params

MCP server

One bin serves both faces. The mcp subcommand starts a stdio MCP server:

npx -y @reneturcios/enginegate mcp

MCP client configuration:

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

Tools

Tool	Input	What it does
unreal	operation (required; one of search, describe, execute, configure), plus per-operation fields: query, tool, action, capability, params, consent	Forwards the call to the running editor's gateway. describe returns a capability's contract — including a consent grant for destructive capabilities, which must be passed back as consent to execute them.

Forwarded calls are JSON-RPC tools/call requests for the tool name unreal. The editor endpoint may answer with a plain JSON body or a server-sent-events stream; both are parsed, and the editor's own result text (and error flag) is what the caller receives.

Development

npm install
npm run build   # tsc -> dist/
npm test        # node test runner over test/*.test.ts, no network
npm run dev     # run the CLI from source via tsx

License

MIT — see LICENSE.