Limits with UEFN
This page says what agents cannot do in UEFN, and how to tell what has really been checked.
No automatic playtest
Section titled “No automatic playtest”No agent plays in your place. Nothing moves a character, presses a button in the game or listens to a sound.
If your editor exposes these tools, an agent can start a session, send changes to it and read the Verse traces. These are clues, not a test: a running session does not show what players see and hear. The Tester specialist separates what succeeded, what failed and what was not run.
When an agent stops (task finished, question, limit reached), the À vous de jouer (Your turn) notification appears. It does not mean that a test took place. Try the game, then reply in the conversation. Multiplayer cases are also left to you.
No mouse and keyboard control
Section titled “No mouse and keyboard control”Agents do not click in windows. Everything goes through the editor’s tools. With no tool, the step is manual and the agent must give you the exact path.
Based on the methods provided, this is the case for:
- creating a Creative prop from a 3D model;
- importing a font;
- setting a widget’s animation keys;
- settings that the editor accepts and then ignores: reading them back shows that they have not changed.
Reliance on the editor’s tools
Section titled “Reliance on the editor’s tools”- The version matters. Epic adds and renames tools from one version to the next. Some, such as scripts, are in beta.
- The options matter. Without Python Editor Scripting and UEFN MCP Toolsets, some of the tools do not appear.
- The editor can freeze. Epic reports stutters and freezes during calls. A long Python script blocks the editor until it finishes.
- Not everything is accessible. The MCP server does not give access to all of Unreal Engine. It does not publish your island and does not open your private statistics.
A working connection does not validate gameplay, performance or publication.
Editing by hand at the same time
Section titled “Editing by hand at the same time”It is possible: Island Pilot does not lock UEFN, and reservations do not apply to you. The agent does not see your actions until it reads the editor’s state again, so it may work on outdated information.
- Avoid touching what an agent is in the middle of changing.
- Save your work before starting an important task.
- After a change of your own, ask the agent to read again before it continues.
- Do not switch islands during a mission: the identity check blocks what follows and the result remains to be checked.
For files, a write is refused if the file has changed since it was read. The agent then has to read it again.
The four kinds of evidence
Section titled “The four kinds of evidence”These four stages cannot be deduced from one another.
| Evidence | What it establishes | What it does not establish |
|---|---|---|
| Report | What the agent says it did and checked at that moment | That it is right, or still true today |
| Export | A file exists in the project | That it is in UEFN |
| Import | The asset exists in UEFN | How it looks, its scale in the game, whether it works |
| In-game test | What you observed in that scenario | The other cases, the other players |
A compile with no errors is one more piece of evidence, a narrower one: the code is valid, which says nothing about how it behaves.
On the Assets page, a version moves to Importé dans UEFN (Imported into UEFN) or Testé (Tested) only when you add evidence with Ajouter une preuve (Add evidence). Neither a successful call nor an agent’s reply is enough.