Connect Claude Code, Codex, Gemini CLI or Cursor to Unreal Engine

Which route fits your agent

Cosindra has two ways in, and both use the same local MCP server and the same editor plugin. In Cosindra Desktop, the agent runs as the chat in the app, on your own subscription or API key. With the extension, the agent stays in VS Code, Cursor or your terminal. Desktop and extension can be installed side by side; they share one server and one editor session.

Step 1: put the plugin in your project

Every route starts by putting the CosindraMCP plugin into your project. The extension does it with its Set up project button (see the Cursor and VS Code steps below). With the desktop app:

1. 1.Download Cosindra Desktop for Windows 10 or newer, or macOS 12 or newer on Apple Silicon, install it and sign in or create a free account. The Windows installer is not code-signed yet, so SmartScreen asks you to choose More info, then Run anyway; the macOS build is signed and notarized.
2. 2.Click Select Project and pick your .uproject; recent Unreal projects are detected for you. The app reads the engine version and puts the matching prebuilt CosindraMCP plugin into the project's Plugins folder. No compiler is needed, so Blueprint-only projects work as they are.
3. 3.Launch the editor from the app. The local server starts alongside it.
4. 4.Check the editor's Output Log for this line: CosindraMCP: Connected to MCP Server!

• •Install guide: Windows and macOS, the SmartScreen notice, signing in
• •Connect your Unreal project: project selection, the automatic plugin install and what to check if the editor does not connect

Claude Code

Inside Cosindra Desktop: open Settings, AI Agents, and click Install on the Claude card. Sign in with your Claude Pro or Max subscription (Open login terminal runs claude login for you), or paste an Anthropic API key in Settings. Then pick Claude in the agent menu at the top of the chat and ask for something in the open level. The app installs agents with npm, so Node.js has to be on the machine.

In your terminal, with the extension: Claude Code reads its own configuration, not your editor's, so the extension writes it for you.

1. 1.Install the Cosindra extension in VS Code or Cursor, open the Cosindra panel in the activity bar and click Sign in, by password or with Google or GitHub. Signing in also downloads the local server.
2. 2.Close the Unreal Editor, then click Set up project. The extension finds the .uproject in the open folder, installs the matching plugin into Plugins and offers to open the editor.
3. 3.Run Connect Claude Code or Codex from the panel or the command palette and choose to write .mcp.json in this project. It asks before writing, keeps any other servers already in the file, and adds one named cosindra-ue5. If you would rather run it yourself, the same menu copies a claude mcp add command instead.
4. 4.Restart Claude Code in the project so it reads the new entry, then ask it for something in the open level.

Codex

Inside Cosindra Desktop: Settings, AI Agents, Install on the Codex card, then sign in with your ChatGPT Plus or Pro subscription through Open login terminal, or use an OpenAI API key from Settings. Pick Codex in the chat's agent menu.

In your terminal, with the extension: Codex reads its own config, never the editor's, so you add the entry once.

1. 1.Install the extension, sign in and run Set up project with the editor closed, as in the Claude Code steps.
2. 2.Run Connect Claude Code or Codex and choose Show the raw server entry. It copies the cosindra-ue5 entry, the launcher command and its arguments, to the clipboard.
3. 3.Add that command and its arguments as an MCP server in Codex's own configuration (~/.codex/config.toml), then restart Codex.
4. 4.Ask Codex for something in the open level. The entry points at a launcher, not a port, so it keeps working when the local server restarts.

Gemini CLI

Gemini CLI connects through Cosindra Desktop. The app's agent list says it needs a Gemini API key; it does not use a Google account login there. The extension's connect command is written for Claude Code and Codex, so this guide does not cover a terminal setup for Gemini CLI.

1. 1.Install Cosindra Desktop and connect your project as in step 1.
2. 2.Make sure Node.js is installed: the app installs agents with npm and shows a notice when Node.js is missing.
3. 3.Open Settings, AI Agents, find Gemini CLI under More agents and click Install.
4. 4.Paste your key into the Gemini API Key field in Settings.
5. 5.Pick Gemini CLI in the agent menu at the top of the chat and ask for something in the open level.

Cursor

Cursor installs extensions from Open VSX, not from Microsoft's Marketplace, so search there. You can also run Cursor's agent inside Cosindra Desktop from the Cursor card under Settings, AI Agents, on your Cursor subscription.

1. 1.Open Cursor's Extensions view, search for Cosindra and install it. The folder you open must be trusted (Workspace Trust), because the extension starts a local process and writes into your project.
2. 2.Open the Cosindra panel and click Sign in.
3. 3.Close the Unreal Editor and click Set up project. The extension installs the matching prebuilt plugin and offers to open the editor.
4. 4.Click Add MCP Server to Cursor. Cursor opens its own dialog with the entry filled in; confirm it once. If you prefer a file, the same action can write ~/.cursor/mcp.json after asking.
5. 5.Ask Cursor's agent for something in the open level.

• •Cosindra for Cursor: the Open VSX link and the Cursor steps on one page

VS Code with GitHub Copilot

VS Code has its own API for extensions to register MCP servers. The Cosindra extension (VS Code 1.101 or newer) uses it, so Copilot needs no configuration file.

1. 1.Search for Cosindra in VS Code's Extensions view, or install it from the Visual Studio Marketplace.
2. 2.Open the Cosindra panel and click Sign in.
3. 3.Close the Unreal Editor and click Set up project, then let it open the editor.
4. 4.Switch Copilot Chat to agent mode: it lists the Unreal tools as soon as set-up is done. Ask mode does not call tools.

• •Cosindra for VS Code: the Marketplace link and the VS Code steps
• •IDE extension reference: where each file goes, the settings, and what to check when an agent sees no tools

Check that the agent is connected

• •The editor's Output Log shows CosindraMCP: Connected to MCP Server! once the plugin reaches the local server.
• •In VS Code or Cursor, run Cosindra: Show Connection Status from the command palette. It says what the extension sees: server, project, editor and sign-in.
• •An agent that sees no tools is almost always reading its own configuration. For Claude Code and Codex, run Connect Claude Code or Codex again and restart the agent; for Cursor, check that the entry is in Cursor's MCP settings.
• •In the editor, open Edit, Plugins and confirm CosindraMCP is listed and enabled, then restart the editor.
• •Still stuck? In the Cosindra panel, Details, Copy diagnostics puts versions, connection state and the last 200 log lines on your clipboard with tokens removed, for a message on the contact page.

What the agent can do in the editor

The plugin exposes 328 editor tools across Blueprints, actors, materials, Enhanced Input, UMG, animation, audio and more. You do not call them by name: describe the change, and the agent picks the tools, calls them and reads the results. A few of them:

• •The full tool reference: all 328 tools by category, with exact names and descriptions

What you need

• •Windows 10 or newer, or macOS 12 or newer on Apple Silicon. There is no Intel Mac build.
• •An Unreal Engine 5.7 or 5.8 project. Blueprint-only projects work; no compiler is needed.
• •Cosindra Desktop (free), or the free extension in VS Code 1.101 or newer or in Cursor. You do not need both.
• •A Cosindra account with a paid plan, from $9.99 a month with BYOK, or the 10-day trial every new account gets without a card.
• •Your agent and its own subscription or API key, paid to its vendor.
• •Node.js, if you install agents inside the desktop app.
• •An internet connection: the editor connection is local, but the models run in the cloud.

Limits

• •Unreal Engine 5.7 or 5.8 only. Projects on other versions are not supported, and no Cosindra product connects to the Unity or Godot editor.
• •Without a paid plan or the trial, a tool call from your own agent answers with an upgrade message instead of running. The desktop app's built-in assistant uses the same tools on Cosindra credits instead.
• •Install or update the plugin with the Unreal Editor closed: the extension refuses to replace a plugin the editor holds open.
• •In a restricted (untrusted) workspace, the extension does not activate.
• •Gemini CLI is documented here through the desktop app only, with a Gemini API key.
• •The agent makes real changes through editor operations. Review what it built, the way you would review a teammate's work.
• •Your project files stay on your machine, but your agent's provider receives your prompts and the tool results. The local server reports tool-call counts, never project contents, to your account for plan limits.

Related pages

• •Unreal MCP in UE 5.8 vs Cosindra: Epic's five setup steps, its limits, and when each fits
• •Download Cosindra Desktop: Windows and Apple Silicon macOS
• •The VS Code and Cursor extension