Troubleshooting & FAQ

Common setup problems and the questions people ask while evaluating the plugin.

My agent can't see the `call` tool

The Unreal Editor must be open and the plugin enabled — the server runs inside the editor process.
Check the agent's config points at the right URL and port (default http://127.0.0.1:19880/mcp). If you enabled auto-derive or set a custom HttpPort, use the resolved port shown on the setup screen.
Some clients add project-file servers disabled by default (e.g. Cursor) — enable it in the client's MCP settings.
Re-run the in-editor setup screen (Tools → Editor Automation Setup) to rewrite the config.

“Port already in use” / two editors collide

By default every project binds the fixed port 19880, so two editors at once collide and the loser refuses to serve. Enable Auto-derive Port From Project Path in Project Settings to give each project a distinct port, or set a fixed HttpPort. On a rare cross-folder hash collision (or an OS-reserved port), set an explicit HttpPort, re-run onboarding, then restart. Also confirm no other local process holds the port.

Connection works but a call fails on this engine version

Some features need a newer Unreal version than the one you're running; those return a clear UNSUPPORTED_ENGINE_VERSION rejection rather than failing silently. The plugin supports UE 5.3–5.8 — confirm you installed it for the engine version you're using.

Don't probe the endpoint by hand

Don't hit the gateway with curl, Invoke-RestMethod, a browser, /health, or legacy /rpc paths. Those bypass the MCP contract and aren't supported. Always go through your agent's call tool.

FAQ

Is any of my project data sent anywhere?

No. The plugin is a local, loopback-only server inside your editor. It sends nothing to us or any third party. Your AI agent is the only thing talking to it, over 127.0.0.1.

Where is the full list of RPCs?

It's self-documenting and lives inside the tool, for your agent to browse on demand — call() for the index, call("namespace") for a page. There's no 1,200-entry catalog to read on this site; that surface is built for the agent, not for hand-browsing. See Concepts.

Will it work in a packaged game build?

No. The module is editor-only by design. It's a development tool, not a runtime feature.

Can it break my project?

It has write access to assets — it can create, edit, and delete them. Work on a branch, commit before large automated changes, and review the diff. Round-tripping graphs to text makes those diffs reviewable in git.

How do I get access after buying?

Purchase on Fab, then request access with your Fab order number and GitHub username. We confirm the order and send a GitHub invite to the private repository (updates and issue tracker). It's a manual review, so it isn't instant.

What does the price do at 1.0?

Early Access is $20 and rises to $50 at the 1.0 release. Buy during Early Access and you keep every update at no extra cost — early buyers are never charged again.

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