Universe Editor MCP

VS Code extension that exposes Universe Editor's tool surface to GitHub Copilot Chat (Agent mode) and any other VS Code MCP-aware client through the Model Context Protocol.

The extension bundles a stdio MCP server which forwards each tool call to the running Universe Editor (UE4Editor.exe) over a Windows named pipe (\\.\pipe\universe-editor-mcp-<pid>). The editor-side EditorMcpService listens on universe-editor-mcp-<pid>, where <pid> is that editor process's own id. When several UE4Editor.exe instances are running, the extension lets you pick which one to connect to.

Requirements

• VS Code 1.101+ (the version that introduced mcpServerDefinitionProviders).
• Windows (the bridge connects through Windows named pipes).
• A running Universe Editor on the local machine. The extension does not start the editor.

Provided MCP tools

• ue_list_tools — list every Universe Editor tool, with optional name / category filters and a summary-only mode.
• ue_create_session — create a tool-call session bound to an editor object (defaults to whichever object is currently active in the editor).
• ue_call_tool — call a Universe Editor tool inside a session.
• ue_get_session / ue_close_session — inspect / close a managed session.

Selecting an editor

On activation the extension enumerates running UE4Editor.exe processes:

• 0 processes — a warning is shown and no server is registered.
• 1 process — it is selected automatically.
• Multiple processes — a Quick Pick prompts you to choose, showing each process's PID, executable path, and command line.

Run the Universe Editor MCP: Reconnect (Select Editor) command (universeEditorMcp.reconnect) to re-run the selection — for example after starting or restarting an editor.

Settings

Changing either setting causes VS Code to re-resolve the MCP server.

Local development

cd extension
npm install
npm run build      # bundles ../src into out/bridge.mjs and compiles extension.ts
code --extensionDevelopmentPath=.

In the launched window, open Copilot Chat in Agent mode and the universe-editor server should appear under MCP: List Servers.

Packaging

cd extension
npm run package    # produces universe-editor-mcp-<version>.vsix

The resulting .vsix contains only out/ plus this README — no node_modules tree, because the bridge is bundled by esbuild.