CarlxsMG/UEAgent

The MCP server for Unreal Engine 5, built into the editor.
More than 1,500 tools that let Claude Code, Cursor or any MCP client build in Unreal,
with every change checked before it runs and read back after.
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UEAgent is an Unreal Engine 5.7 and 5.8 editor plugin that lets AI agents operate the editor through the
Model Context Protocol. The plugin is the server: it serves
Streamable HTTP from inside the editor, with no Python or Node process in between.
## Why UEAgent
The whole engine, not a demo. Blueprints and their graphs, materials, animation (AnimBP,
montages, IK, Pose Search), Niagara, landscapes and foliage, World Partition, PCG, Sequencer,
UMG/CommonUI/MVVM, GAS, AI (Behavior Trees, StateTree, EQS, Smart Objects), audio and MetaSounds,
USD and Interchange, PIE control and inspection: see the tool reference.
Verified, not assumed. An editor call that answers success: true proves nothing, so every
call goes through a contract:
preconditions refuse the calls known to crash or freeze the editor, and say what to do instead;
readback re-reads the state after the call, and reports as failed a write that did not stick,
a zero that proves nothing or a change that landed in the wrong PIE world.
Safe with your content. Every tool call is one undo step, named after the tool, so Ctrl+Z
reverts it. Vendored libraries listed as Read Only Content Roots cannot be saved, renamed,
moved or deleted by any tool, and calls that are unreliable while Play-in-Editor runs are refused
while it runs.
Built for real sessions. Several agents can share one editor: protocol work runs on network
threads, and every tool call runs on the game thread through one queue. The Activity panel
(status bar > MCP > Activity) lists each call with its duration and outcome.
mermaid
flowchart LR
A["AI agent Claude Code, Cursor, ..."] -- "MCP over HTTP" --> P
subgraph E["Unreal Editor + UEAgent"]
P["Preconditions refuse known crashes"] --> H["Tool 1,500+ of them"] --> R["Readback re-read the state"]
end
R -- "verified result" --> A
How a server inside the editor differs from one outside it, and the questions to ask any MCP server
for Unreal: Choosing an MCP server.
## Quick start
Let your agent do it. Open Claude Code, Cursor, Codex or another agent in your project's folder and
paste:
Install the UEAgent plugin in this Unreal Engine project and connect yourself to it, following https://raw.githubusercontent.com/CarlxsMG/UEAgent/main/llms-install.md
It does the steps below, checks the download's SHA-256 and asks before it changes anything; you reload
its MCP servers at the end. See llms-install.md. Or by hand:
1. Install. Download the latest UEAgent--UE5.8-Win64.zip (or -UE5.7-, for your engine) from
Releases and unzip it into
/Plugins/, or build it from source.
2. Open the project. The status bar shows MCP · 55561 with a green dot once the server is up
(if it does not, see Troubleshooting).
3. Connect an agent. From that status-bar menu, Connect Claude Code to this project writes the
unreal entry of your project's .mcp.json, and Connect another client does the same for
Cursor, VS Code, Antigravity CLI and OpenCode (and copies the command for Codex). Or, for yourself