Work on your UEFN project with AI

UEFN Skills

Use dedicated skills for UEFN editor tasks, Verse and Fortnite props.

Supported platforms: uefn. Beta.

What you can build

  • A dependency-free local MCP safety broker that shares one upstream handshake across clients, keeps reads available, and gives one mutating client an automatic renewable five-minute writer lease
  • Generation-aware recovery that retries a read once after an editor restart but never replays an ambiguous mutation
  • Live-schema validation and local circuit breakers for unknown tools or arguments, duplicated prefixes, empty searches, unsafe imports, same-level reloads, repeated per-actor saves, and revision-control checkout failures, plus a compile-before-push breaker that refuses a push while Verse is unbuilt, an outright refusal of entity deletion, and script-aware versions of both that read the body of a batched tool script
  • A compile-before-push gate carried as doctrine, not as advice: save, build, read the diagnostics array, fix every Error row, and only then push, because a push carrying compile errors opens a modal that wedges every later call until a human closes it
  • A call cheat sheet corrected against a live v42 editor rather than against the documentation, including the argument names that are silently ignored, which is how a filtered call quietly returns the whole level
  • Redacted log responses capped at 64 KiB plus privacy-preserving broker events in .playugc/uefn/broker-events.jsonl
  • A router skill with one compact always-on safety block that sends work to exactly one domain skill without repetitive preflight narration
  • One mechanism per feature: Scene Graph entities and Creative devices are two object models that do not interoperate, and the mechanism skill makes the choice explicit before anything is built
  • Verse coverage for the errors that stop a build: two vector and rotation types in scope, effect specifiers, named optional parameters, spawns that need a suspending context, and setters the API simply does not have
  • Lighting, fog, exposure, and post-process handled through the overrides that make a successful property write produce no visible change
  • Items, granters, spawners, and key-and-lock gates, including why Missing Items appears and what to do about it
  • Typed verification evidence from SOURCE_PASS through RUNTIME_PASS and MULTICLIENT_PASS, replacing ambiguous bare PASS claims
  • A UI skill that says which of the UEFN UI surfaces a HUD, menu or scoreboard belongs on, what has no equivalent in Verse (fonts, corner radius, geometry read-back), and how to check a layout numerically instead of by eye
  • A shipped index of 26,620 Fortnite props and 2,169 creative galleries, searched the way you talk: say "a rusty corrugated wall" or show a mockup and your AI finds real Fortnite assets by everyday words, with a precise first pass and a documented widening ladder for when a word returns nothing. No extra tools, no downloads, no account
  • See it before it lands: a live rendered preview of each candidate prop, and two or three choices to pick from rather than one silent guess
  • Places what you picked, snapped to the ground and filed in an outliner folder, using the prop identity that keeps full Creative prop behaviour instead of a bare mesh
  • Honest availability: 1,348 of the indexed assets are unreachable this season and are flagged as such in the data, so your AI says "unavailable" once instead of retrying a path that cannot load
  • Real prop dimensions in centimetres for every measurable asset, so a run of walls or a hedge line is spaced off the actual size rather than eyeballed
  • An optional advanced route for builders who want the mesh and texture FILES: export with a machine-readable manifest, convert, import under your own project mount, and rebuild the material from the manifest rather than from filename guesses
  • The three import failures that look like bugs and are not, each with the actual cause: a mesh a hundred times too small, a mesh that renders white, and foliage that renders as solid rectangles instead of leaves
  • An ordered verification ladder for a placed or imported asset, strongest evidence first, including which editor thumbnail is lying to you after a material change
  • A gotchas catalog of live-verified UEFN traps (symptom, proven cause, fix) consulted before any diagnosis loop, covering prop damage at altitude, spawned-vs-placed prop behavior, validation lockouts, silent write no-ops, and zone clamping
  • A materials and FX skill that names the exact MCP toolset for every visual job (material graphs, instances, a second mesh pass, textures, Niagara) and carries the verified prop-outline recipe, including the trap that Epic's Overlay Material renders nothing on creative-prop components
  • Sixteen reference files behind the thirteen skills, opened only when a skill sends the agent there, plus the asset index, which is grepped a line at a time instead of read

Before you start

  • UEFN: the editor these skills drive. Every skill assumes a UEFN project open in the editor with its MCP server reachable, and none of them does anything useful without one.
  • Node.js 18.17+: runs the local safety broker. The broker has no third-party runtime packages.
  • Blender: OPTIONAL, advanced only. Converts an exported Fortnite mesh from .glb to .fbx, because UEFN's FBX importer rejects .glb outright, and writes the dimension sidecar that proves an import came in at the right scale. Nothing in the main flow needs it: finding, previewing and placing Fortnite props runs on the shipped asset index and the stock editor MCP alone. Install it only to extract mesh and texture FILES out of the archive.
  • FortnitePorting MCP server (fortnite-assets): OPTIONAL, advanced only. Reads the installed Fortnite archive so your AI can export Fortnite's own meshes and textures as files. Finding, previewing and placing Fortnite props does NOT need it: the kit ships a 26,620-prop index and the stock editor MCP does the rest. Install it only to extract asset files. Register it with: claude mcp add fortnite-assets --scope user --env FPMCP_CONFIG=<path to config.json> -- <path to>\publish\mcp\FortnitePorting.Mcp.exe

Scope and limitations

  • macOS support. UEFN itself is Windows only, so this kit is Windows only for the same reason.
  • Roblox tooling. Nothing here touches Roblox, Luau, or Roblox Studio; the PlayUGC Roblox kits are separate.
  • The upstream UEFN MCP server itself. The included broker wraps the server you supply; it does not replace the editor integration.
  • Verse or device code you can paste in. These are operating skills, not a code library.
  • Manifest-driven scene reconciliation, checkpoint bundles, build-receipt deduplication, automated recovery, or runtime test packets. Those remain P1.
  • Editor mutations while UEFN is closed. The broker health endpoint can run, but UEFN calls still require the live editor.
  • Items, weapons, and outfits in the asset index. It indexes props and creative galleries; item and weapon identifiers are the items skill's job, and outfits are not indexed yet.
  • Colour search. The index knows what a thing is, not what colour it is: there is no orange or terracotta token, so a colour in your mockup is matched through the material or set name instead, which the skill tells your AI to do.
  • Assembly instructions for modular pieces. Rows that are one unit of a larger shape are flagged, but the index carries no pivot data. The asset skill now carries the measured procedure instead: place one piece, read its bounds, derive the rotation offset once, and tile off the measured seam rather than off the listed size.
  • Assets Epic has not shipped to Creative this season. 1,348 of the 26,620 indexed rows are unreachable right now, and the data flags each one rather than hiding it; they come back when Epic exposes their mounts again.
  • A verified status for every mount. 35 of the 273 mounts have been driven against the live editor and 7 are confirmed absent; the remaining 231 are marked unverified, which means untested rather than broken.
  • A live catalog. The index is a snapshot of Fortnite 42.00 and is refreshed on a seasonal cadence, so a brand-new prop is not in it until the next refresh, and the live editor always wins a disagreement.
  • Character and skeletal asset import. Outfits and weapons export cleanly and their manifests are correct, but the UEFN-side skeletal import path is unproven, so the asset skill covers static meshes only.
  • Automatic island publishing. Nothing in this kit publishes; a publish validation pass is something the skills tell you to run, not something they run for you.
  • Perfect colour fidelity on Fortnite's layered shaders. Frosted-glass panels, vertex-colour hue shifts, and multi-layer atlases are not carried by the export at all, so the asset skill grades those WARN and says which one applies instead of chasing them.
  • The Fortnite asset server and Blender themselves. Both are external tools the asset skill drives; the kit ships neither.

Start 7-day trial ยท $67/month per developer. Card required. AI subscriptions and optional service costs are separate.