The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the Loomle MCP for Unreal listing page.
Loomle is an agent-native Unreal Engine integration for reading and changing complex editor objects through SAL, the Structured Agent Language.
SAL turns Blueprint graphs, Widget trees, Class reflection, Assets, and other non-text UE state into compact, ordered text that both people and agents can read, copy, discuss, and patch. It stays faithful to UE: native paths, types, field names, values, palette actions, compiler diagnostics, and editor semantics remain native instead of being replaced by a parallel JSON model.
Text code already gives agents precise search, references, diffs, and edits. Unreal assets do not. Loomle supplies that missing text workflow while keeping the editor and UE APIs as the source of truth.
The standalone Client exposes eight MCP tools:
status: inspect the Client version, update availability, and bound session
and Bridge health.project: inspect project availability and bind this MCP session to one
Unreal project.sal_query: execute one self-contained SAL Query Text.sal_patch: execute one ordered SAL Patch Text.sal_schema: discover the resident SAL guide and the active interface cards.agent_skill: discover and load MCP-managed Loomle workflow Skills without
a separate agent-specific installation.editor: observe the current Unreal interaction with empty arguments, or
open, focus, and close an exact Blueprint or Graph from canonical SAL Target
Text.python: run unrestricted Unreal Editor Python only as a fallback for
capabilities not covered by a structured Loomle interface, and poll an
execution only when the initial result supplies a continuation.The current public SAL modules are Asset, Blueprint, Class, Graph, StateTree, and Widget. They cover Asset Registry discovery, Blueprint declarations and components, Class reflection and defaults, graph-local flow and mutation, StateTree hierarchy and bindings, Widget trees, factual reference queries, compilation, save, and editor context.
Example:
Use sal_schema({}) for the active module index and
sal_schema({ module: "graph" }) for one exact interface card. Supported exact
reads and Palette Entries provide dynamic discovery with with schema; each
interface card states the exact subjects that accept it.
The latest stable Loomle release is available from GitHub Releases for Unreal Engine 5.7 and 5.8. Choose the package matching the installed engine version:
| Package | Contents |
|---|---|
loomle-bridge-ue5.7.zip | Complete UE 5.7 plugin for Mac Apple Silicon and Windows x64 |
loomle-bridge-ue5.8.zip | Complete UE 5.8 plugin for Mac Apple Silicon and Windows x64 |
These stable filenames always resolve through the latest final GitHub Release. That release also retains immutable, versioned copies of both archives.
The Fab listing provides the current marketplace-approved Loomle build. GitHub Releases may be newer while a Fab update is under review.
The complete archive contains both native targets and their matching Clients:
The executable under Resources/Loomle is the self-contained SAL Client. It
requires no separate Python, uv, Node.js, global Loomle install, or
project-local Client.
Before upgrading from 0.6, close Unreal Editor and remove or move the old
<Project>/Plugins/LoomleBridge directory. A same-named project plugin takes
precedence over the new engine plugin and would keep loading 0.6.
Extract the complete archive, then copy the LoomleBridge directory
to:
Enable LoomleBridge, restart Unreal Editor, and configure an MCP server named
loomle to launch the bundled Client with the argument mcp:
Full instructions: https://loomle.ai/install.html
LoomleBridge enabled.status once to inspect Client, update, session, and Bridge health.project to inspect or bind the intended
project.editor({}) to begin from the user's current editor state; use
editor({ operation: "open" | "close", target }) for exact Blueprint or
Graph presentation control.sal_schema when the target module or exact operation is unfamiliar.sal_query, dry-run changes with sal_patch, then apply and
finalize through the owning asset.See https://loomle.ai/quickstart.html for a complete first query and patch.
The Client discovers live Bridge instances through
~/.loomle/state/runtimes. This directory is runtime discovery state, not a
global installation. Each MCP session keeps one sticky project binding and
validates that project's current Editor with a short live health probe. If the
bound project is offline, Loomle reports that state and never falls through to
another online project. Use project({}) to inspect candidates and bind or
switch explicitly when needed.
The repository has four current product boundaries:
sal/: language parser, normalized model, schemas, and TypeScript SDK.interfaces/: resident guide and static UE interface cards.client/: standalone MCP Client.engine/LoomleBridge/: Unreal Editor plugin.Install workspace dependencies and run the TypeScript test suite:
Build and test the native Client for the current supported runner:
Run the complete Loomle UE Automation category against a same-commit development plugin compiled with the native tests:
The output directory must not already exist. Raw plugin source is not a runnable candidate. The final release archive intentionally excludes native test code, so it is not the complete Automation candidate.
Run the small packaged Client-to-UE workflow against the exact audited release archive and its bundled Client:
Release assembly consumes only the canonical program at
.tmp/client/<platform-arch>/loomle(.exe) and combines it with the Bridge
source plugin. See packaging/client/ and packaging/fab/ for the artifact
contracts.
Repository and product design documents live under docs/; canonical SAL and
UE interface contracts live under sal/docs/ and interfaces/. Loomle 0.6
source and documents remain available from the 0.6 branch, its release tags,
and repository history; main contains only the current design and code.
Loomle is open source under the MIT License. See LICENSE.