Monolith is an MCP server tool designed as an Unreal Engine editor plugin, developed by tumourlove. It provides extensive read and write access to Unreal Engine projects, enabling powerful interactions for developers and AI assistants. Operating on the mcp platform, it requires Unreal Engine 5.7+ and optionally Python 3.10+ for C++ source indexing. This tool exposes over 1,400 actions across more than 25 namespaces, covering detailed operations within Blueprints and Niagara systems. It supports HTTP and stdio transport protocols, making it compatible with various AI clients like Claude Code and Cursor.

What does Monolith connect to?

Monolith functions as an Unreal Engine editor plugin, establishing a direct connection to Unreal Engine projects. It provides full read and write access, enabling deep interaction with project assets and configurations. Its primary role is as an MCP server, allowing external clients, including AI assistants, to query and modify project elements. This connection model positions Monolith as a central hub for programmatic control and analysis of Unreal Engine development environments, enhancing automation capabilities significantly.

Core features and tools

The tool exposes callable actions through a namespace dispatch pattern, where each domain offers a single {namespace}_query(action, params) tool. A central monolith_discover() call lists all available actions, providing over 1,400 actions across more than 25 namespaces. Key capabilities include detailed Blueprint manipulation, such as reading graph topology, tracing execution flow, inspecting variables, creating new Blueprints, and modifying components. For Niagara, actions like get_custom_hlsl_text and set_custom_hlsl_text are examples of available functionality.

Who is it for?

Monolith targets developers and AI assistants actively engaged with Unreal Engine projects. It supports concrete workflows like AI creating new Blueprints from descriptions, surgically modifying existing Blueprints, and performing "Reflection Intelligence" queries. These queries encompass decision, risk, C++ reflection, and replication analyses. This tool is valuable for automating complex tasks and enabling AI-driven development within the Unreal Engine ecosystem. Skip this if your work does not involve Unreal Engine or deep programmatic interaction with its projects.

How to get started

No credentials are required. The server starts a local HTTP server on port 9316, which is reachable on all network interfaces by default.

Use cases

• AI creating new Blueprints from a description.
• AI surgically modifying existing Blueprints.
• AI performing Reflection Intelligence queries (decision, risk, C++ reflection, and replication queries).

Monolith stands as a powerful MCP server tool for Unreal Engine, providing granular control over project assets and supporting advanced AI integration. Its extensive action set for Blueprints and Niagara, coupled with stdio and HTTP transport, makes it a versatile platform for automated development. While offering deep access, users must manage network security.