Monolith

One plugin. Every Unreal domain. Zero dependencies.

What is Monolith?

Monolith is an Unreal Engine editor plugin that gives your AI full read/write access to your project through the Model Context Protocol (MCP). Install one plugin, point your AI client at one endpoint, and it can work with Blueprints, Materials, Animation, Niagara, project configuration, and more.

It works with Claude Code, Cursor, or any MCP-compatible client. If your AI tool speaks MCP, it speaks Monolith.

Platform: Windows only. Mac and Linux support is coming soon.

Why Monolith?

Most MCP integrations register every action as a separate tool, which floods the AI's context window and buries the actually useful stuff. Monolith uses a namespace dispatch pattern instead: each domain exposes a single {namespace}_query(action, params) tool, and a central monolith_discover() call lists everything available. Small tool list (12 tools), massive capability (291 actions across nine domains). The AI gets oriented fast and spends its context on your actual problem.

What Can It Actually Do?

Blueprint — The AI has full read/write access to every part of a Blueprint. It can read graph topology, trace execution flow, inspect variables, components, functions, and interfaces. It can create new Blueprints from any parent class, add/remove/rename variables and components, build out functions and event dispatchers, wire up nodes, set pin defaults, implement interfaces, reparent, compile, and validate. Hand it a description and it'll build the whole Blueprint. Or give it an existing one and it'll surgically change what you need.

Material — Create materials and instances from scratch, add and connect expression nodes, set scalar/vector/texture parameters, build full PBR graphs programmatically, recompile, validate for errors, and read compiled shader stats. "Give me a worn leather material with edge wear and a normal map input" is a reasonable thing to ask.

Animation — Inspect and modify animation sequences, montages, blend spaces, Animation Blueprints, state machines, skeletons, and PoseSearch databases. Add/remove notifies, edit montage sections, create blend space samples, trace ABP state transitions. The whole animation pipeline is in scope.

Niagara — Create particle systems from specs, add/remove emitters and modules, set module inputs and bindings, configure data interfaces and renderers, edit parameters, read compiled GPU HLSL, and batch-execute multiple operations atomically. "Build me a blood splatter system that responds to hit direction" — genuinely doable.

Editor — Trigger full UBT builds or Live Coding compiles, read build errors and compiler output, search editor logs, get crash context after failures, query editor state. The AI can compile your code and diagnose the failure without you touching the editor.

Config — Read, search, and diff INI files with full resolution chain awareness (Base → Platform → Project → User). Ask what a setting does, where it's overridden, and what the effective value is. Good for performance tuning sessions where you want the AI to just sort out the INIs.

Project — Full-text search across every indexed asset. Find assets by name, type, path, or content. Trace references between assets. The index updates automatically as assets change and covers marketplace/Fab plugin content too.

Source — Look up any Unreal Engine C++ API: read function implementations, search engine source, get class hierarchies, trace call graphs, verify include paths. The native C++ indexer runs automatically — no Python, no setup. The AI never has to guess at a function signature.

Features

Full Blueprint read/write/CRUD — Create Blueprints, edit variables/components/functions/nodes, compile and validate. Read CDO properties from any Blueprint or DataAsset.
Material graph editing — Read, build, and validate material graphs with preview support
Animation coverage — Montages, blend spaces, ABP state machines, skeletons, bone tracks
Niagara particle systems — Create and edit systems, emitters, modules, parameters, renderers, and HLSL
Editor integration — Build triggers, log capture, compile output, crash context, Live Coding support
Config management — INI resolution, diff, search, and explain
Deep project search — SQLite FTS5 full-text search across all indexed assets, including marketplace and Fab plugin content. Configurable additional content paths.
Engine source intelligence — Native C++ indexer (no Python required) with call graphs, class hierarchy, and cross-references. Optional project C++ source indexing for richer results.
Auto-updater — Checks GitHub Releases on editor startup, one-click update
Claude Code skills — Domain-specific workflow guides bundled with the plugin
Pure C++ — Direct UE API access, embedded Streamable HTTP server, zero external dependencies

Installation

Prerequisites

Unreal Engine 5.7+ — Launcher or source build (unrealengine.com)

Platform: Windows only. Mac and Linux support is coming soon.

Claude Code, Cursor, or another MCP client — Any tool that supports the Model Context Protocol
(Optional) Python 3.10+ — Only needed if you want to index your own project's C++ source. Engine source indexing is built-in and needs no Python.

Step 1: Drop Monolith into your project

Every Unreal project has a Plugins/ folder. If yours doesn't have one yet, create it next to your .uproject file:

YourProject/
  YourProject.uproject
  Content/
  Source/
  Plugins/          <-- here
    Monolith/

Option A: Git clone (recommended)

cd YourProject/Plugins
git clone https://github.com/tumourlove/monolith.git Monolith

Option B: Download ZIP

Grab the latest release from GitHub Releases, extract it, and drop the folder at YourProject/Plugins/Monolith/. The release ZIP includes precompiled DLLs — Blueprint-only projects can open the editor immediately without rebuilding. C++ projects should rebuild first.

Option C: Let your AI do it

If you're already in a Claude Code, Cursor, or Cline session, just say:

"Install the Monolith plugin from https://github.com/tumourlove/monolith into my project's Plugins folder"

It'll clone the repo, create .mcp.json, and configure everything. After it's done, restart your AI session so it picks up the new .mcp.json, then skip to Step 3.

Step 2: Create `.mcp.json`

This file tells your AI client where to find Monolith's MCP server. Create it in your project root — same directory as your .uproject:

YourProject/
  YourProject.uproject
  .mcp.json          <-- create this
  Plugins/
    Monolith/

For Cursor / Cline:

{
  "mcpServers": {
    "monolith": {
      "type": "streamableHttp",
      "url": "http://localhost:9316/mcp"
    }
  }
}

For Claude Code:

{
  "mcpServers": {
    "monolith": {
      "type": "http",
      "url": "http://localhost:9316/mcp"
    }
  }
}

Heads up: Claude Code uses "http", Cursor and Cline use "streamableHttp". Wrong type = connection failure. It's a common gotcha.

Or just copy the template that ships with Monolith:

cp Plugins/Monolith/Templates/.mcp.json.example .mcp.json

Step 3: Open the editor

Open your .uproject as normal. On first launch:

Monolith auto-indexes your project (30-60 seconds depending on size — go get a coffee)
Open the Output Log (Window > Developer Tools > Output Log)
Filter for LogMonolith — you'll see the server start up and the index complete

When you see Monolith MCP server listening on port 9316, you're in business.

Step 4: Connect your AI

Open Claude Code (or your MCP client) from your project directory — the one with .mcp.json
Claude Code auto-detects .mcp.json on startup and connects to Monolith
Sanity check: ask "What Monolith tools do you have?"

You should get back a list of namespace tools (blueprint_query, material_query, etc.). If you do, everything's working.

Step 5: (Optional) Index your project's C++ source

Engine source indexing is automatic — source_query works immediately with no setup.

If you also want your AI to search your own project's C++ source (find callers, callees, and class hierarchies across your own code):

Install Python 3.10+
Run python Plugins/Monolith/Scripts/index_project.py from your project root
Your project source gets indexed into EngineSource.db alongside engine symbols
To re-run the indexer without leaving the editor: source_query("trigger_project_reindex")

Verify it's alive

With the editor running, hit this from any terminal:

curl -X POST http://localhost:9316/mcp \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

You'll get a JSON response listing all Monolith tools. If you get "connection refused", the editor isn't running or something went sideways — check the Output Log for LogMonolith errors.

(Optional) Install Claude Code skills

Monolith ships domain-specific workflow skills for Claude Code:

cp -r Plugins/Monolith/Skills/* ~/.claude/skills/

Architecture

Monolith.uplugin
  MonolithCore          — HTTP server, tool registry, discovery, auto-updater (4 actions)
  MonolithBlueprint     — Blueprint read/write, variable/component/graph CRUD, node operations, compile, CDO reader (67 actions)
  MonolithMaterial      — Material inspection + graph editing + CRUD (47 actions)
  MonolithAnimation     — Animation sequences, montages, ABPs, PoseSearch (74 actions)
  MonolithNiagara       — Niagara particle systems (64 actions)
  MonolithEditor        — Build triggers, log capture, compile output, crash context (17 actions)
  MonolithConfig        — Config/INI resolution and search (6 actions)
  MonolithIndex         — SQLite FTS5 deep project indexer, marketplace content, 15 asset indexers (5 actions)
  MonolithSource        — Native C++ engine source indexer, call graphs, class hierarchy (10 actions)

291 actions total across 9 modules, exposed through 12 MCP tools.

Tool Reference

Namespace	Tool	Actions	Description
`monolith`	`monolith_discover`	—	List available actions per namespace
`monolith`	`monolith_status`	—	Server health, version, index status
`monolith`	`monolith_reindex`	—	Trigger full project re-index
`monolith`	`monolith_update`	—	Check or install updates
`blueprint`	`blueprint_query`	67	Full Blueprint CRUD — read/write graphs, variables, components, functions, nodes, compile, CDO properties
`material`	`material_query`	47	Inspection, editing, graph building, previews, validation, CRUD
`animation`	`animation_query`	74	Montages, blend spaces, ABPs, skeletons, bone tracks, PoseSearch, IKRig, Control Rig
`niagara`	`niagara_query`	64	Systems, emitters, modules, parameters, renderers, HLSL, dynamic inputs, simulation stages
`editor`	`editor_query`	17	Build triggers, error logs, compile output, crash context, scene capture, texture import
`config`	`config_query`	6	INI resolution, explain, diff, search
`project`	`project_query`	5	Deep project search — FTS5 across all indexed assets including marketplace plugins
`source`	`source_query`	10	Native C++ engine source lookup, call graphs, class hierarchy, project reindex

Auto-Updater

Monolith checks for new versions on editor startup so you don't have to babysit GitHub.

On editor startup — Checks GitHub Releases for a newer version
Downloads and stages — If an update is found, it downloads and stages the new version
Auto-swaps on exit — The plugin is replaced when you close the editor
Manual check — monolith_update tool to check anytime
Disable — Toggle off in Editor Preferences > Plugins > Monolith

Troubleshooting

Problem	Solution
Plugin doesn't appear in editor	Verify the folder is at `YourProject/Plugins/Monolith/` and contains `Monolith.uplugin`. Check you're on UE 5.7+.
MCP connection refused	Make sure the editor is open and running. Check Output Log for port conflicts. Verify `.mcp.json` is in your project root.
Index shows 0 assets	Run `monolith_reindex` or restart the editor. Check Output Log for indexing errors.
Source tools return empty results	Run `monolith_reindex()` and wait for completion, then retry. Engine source indexing is built-in — if results are still empty, check the Output Log for `LogMonolith` errors.
Claude can't find any tools	Check `.mcp.json` transport type: Claude Code uses `"http"`, Cursor/Cline use `"streamableHttp"`. Restart your AI client after creating the file.
Tools fail on first try	Restart Claude Code to refresh the MCP connection. Known quirk with initial connection timing.
Port 9316 already in use	Change the port in Editor Preferences > Plugins > Monolith, then update `.mcp.json` to match.
Mac/Linux not working	Windows only for now. Mac and Linux are planned.

Configuration

Settings live at Editor Preferences > Plugins > Monolith:

Setting	Default	Description
MCP Server Port	`9316`	Port for the embedded HTTP server
Auto-Update	`On`	Check GitHub Releases on editor startup
Module Toggles	All enabled	Enable/disable individual domain modules
Database Path	Project-local	Override SQLite database storage location
Index Marketplace Plugins	`On`	Index content from installed marketplace/Fab plugins
Index Data Assets	`On`	Deep-index DataAsset subclasses (15 indexers)
Additional Content Paths	`[]`	Extra content paths to include in the project index

Skills

Monolith bundles 9 Claude Code skills in Skills/ — domain-specific workflow guides that give your AI the right mental model for each area:

Skill	Description
`unreal-blueprints`	Full Blueprint CRUD — read, create, edit variables/components/functions/nodes, compile
`unreal-materials`	PBR setup, graph building, validation
`unreal-animation`	Montages, ABP state machines, blend spaces
`unreal-niagara`	Particle system creation, HLSL modules, scalability
`unreal-debugging`	Build errors, log search, crash context
`unreal-performance`	Config auditing, shader stats, INI tuning
`unreal-project-search`	FTS5 search syntax, reference tracing
`unreal-cpp`	API lookup, include paths, Build.cs gotchas
`unreal-build`	Smart build decision-making, Live Coding vs full rebuild

Documentation

API_REFERENCE.md — Full action reference with parameters
SPEC.md — Technical specification and design decisions
CONTRIBUTING.md — Dev setup, coding conventions, PR process
CHANGELOG.md — Version history and release notes
Wiki — Installation guides, test status, FAQ

Contributing

Contributions are welcome. See CONTRIBUTING.md for dev environment setup, coding conventions, how to add new actions, and the PR process.

License

MIT — See ATTRIBUTION.md for credits.

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Monolith

What is Monolith?

Why Monolith?

What Can It Actually Do?

Features

Installation

Prerequisites

Step 1: Drop Monolith into your project

Step 2: Create `.mcp.json`

Step 3: Open the editor

Step 4: Connect your AI

Step 5: (Optional) Index your project's C++ source

Verify it's alive

(Optional) Install Claude Code skills

Architecture

Tool Reference

Auto-Updater

Troubleshooting

Configuration

Skills

Documentation

Contributing

License

About

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Name		Name	Last commit message	Last commit date
Latest commit History 79 Commits
.claude/agent-memory		.claude/agent-memory
.github		.github
Config		Config
Docs		Docs
MCP		MCP
Scripts		Scripts
Skills		Skills
Source		Source
Templates		Templates
.gitignore		.gitignore
ATTRIBUTION.md		ATTRIBUTION.md
CHANGELOG.md		CHANGELOG.md
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE		LICENSE
Monolith.uplugin		Monolith.uplugin
README.md		README.md

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Monolith

What is Monolith?

Why Monolith?

What Can It Actually Do?

Features

Installation

Prerequisites

Step 1: Drop Monolith into your project

Step 2: Create .mcp.json

Step 3: Open the editor

Step 4: Connect your AI

Step 5: (Optional) Index your project's C++ source

Verify it's alive

(Optional) Install Claude Code skills

Architecture

Tool Reference

Auto-Updater

Troubleshooting

Configuration

Skills

Documentation

Contributing

License

About

Topics

Resources

License

Contributing

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Stars

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Releases 12

Sponsor this project

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Step 2: Create `.mcp.json`

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