unreal-editor-mcp

Build diagnostics and editor log tools for Unreal Engine AI development via Model Context Protocol.

Gives AI assistants the ability to trigger Live Coding builds, inspect parsed compile errors, search/filter editor logs, and get crash context — the "feedback loop" for C++ iteration without leaving the AI workflow.

Why?

When iterating on C++ in UE, the build-test cycle is invisible to AI assistants. They can write code but can't compile it, see if it worked, or read the editor's output. This server closes that loop.

Complements (does not replace):

• unreal-source-mcp — Engine-level source intelligence (full UE C++ and HLSL)
• unreal-project-mcp — Project-level source intelligence (your C++ code)
• unreal-blueprint-mcp — Blueprint graph reading (nodes, pins, connections, execution flow)
• unreal-blueprint-reader — C++ editor plugin that serializes Blueprint graphs to JSON for AI tooling
• unreal-material-mcp — Material graph intelligence, editing, and procedural creation (46 tools: expressions, parameters, instances, graph building, templates, C++ plugin)
• unreal-config-mcp — Config/INI intelligence (resolve inheritance chains, search settings, diff from defaults, explain CVars)
• unreal-animation-mcp — Animation data inspector and editor (sequences, montages, blend spaces, ABPs, skeletons, 62 tools)
• unreal-niagara-mcp — Niagara VFX intelligence and editing (emitters, modules, HLSL generation, procedural creation, 70 tools)
• unreal-api-mcp by Nico Bailon — API surface lookup (signatures, #include paths, deprecation warnings)

Together these servers give AI agents full-stack UE understanding: engine internals, API surface, your project code, build/runtime feedback, Blueprint graph data, config/INI intelligence, material graph inspection + editing, animation data inspection + editing, and Niagara VFX inspection + creation.

Prerequisites

• Python Remote Execution must be enabled in the editor: Edit > Project Settings > search "remote" > under Python Remote Execution, check "Enable Remote Execution?". This allows the server to discover and communicate with the running editor. Without it, log tools still work but build triggering will fail.

Quick Start

Install from GitHub

uvx --from git+https://github.com/tumourlove/unreal-editor-mcp.git unreal-editor-mcp

Claude Code Configuration

Add to your project's .mcp.json:

{
  "mcpServers": {
    "unreal-editor": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/tumourlove/unreal-editor-mcp.git", "unreal-editor-mcp"],
      "env": {
        "UE_PROJECT_PATH": "D:/Unreal Projects/MyProject"
      }
    }
  }
}

Or run from local source during development:

{
  "mcpServers": {
    "unreal-editor": {
      "command": "uv",
      "args": ["run", "--directory", "C:/Projects/unreal-editor-mcp", "python", "-m", "unreal_editor_mcp"],
      "env": {
        "UE_PROJECT_PATH": "D:/Unreal Projects/MyProject"
      }
    }
  }
}

Tools

Build Tools (5)

Tool	Description
trigger_build	Trigger a Live Coding compile via the editor's Python bridge. Returns a build ID for tracking.
get_build_status	Check build state: building, succeeded, or failed. Shows error/warning counts.
get_build_errors	Get parsed build errors with file, line, error code, and message. Filter by module or severity.
get_build_summary	Overview of the latest build: error count, warning count, duration.
search_build_output	Regex search across raw build output from the latest build.

Log Tools (6)

Tool	Description
get_recent_logs	Last N log lines, filterable by category (e.g. LogTemp, LogNet) and severity (Error, Warning, etc).
search_logs	Regex search across the current session's log buffer.
get_log_categories	List all active log categories with their message counts.
get_crash_context	Last Fatal log entries + crash report directory info from Saved/Crashes/.
tail_log	Recent log output (last N seconds).
get_log_stats	Error/warning breakdown per category, most active categories.

Environment Variables

Variable	Required	Description
UE_PROJECT_PATH	Yes	Path to the UE project root (containing the .uproject file)
UE_EDITOR_PYTHON_PORT	No	TCP port for command connection (default: 6776)
UE_MULTICAST_GROUP	No	UDP multicast group for editor discovery (default: 239.0.0.1)
UE_MULTICAST_PORT	No	UDP multicast port (default: 6766)
UE_MULTICAST_BIND	No	Multicast bind address (default: 127.0.0.1)

How It Works

Editor Bridge — Discovers the running UE editor via UDP multicast (the same protocol as UE's built-in remote_execution.py). Opens a TCP command channel to execute Python in the editor. Used to trigger Live Coding compiles via LiveCoding.Compile console command.

Log Tailer — A background thread polls the project's Saved/Logs/{ProjectName}.log every 500ms. On startup, reads the last 1000 lines to pre-populate. Maintains a rolling buffer of 10,000 parsed log entries in memory. All log tools query this buffer.

Build Manager — When a build is triggered, monitors LogLiveCoding log entries to detect completion ("Live coding succeeded" / "Live coding failed"). Parses MSVC error format (file(line): error C1234: message) from build output. Keeps a rolling history of the last 5 builds.

No database — all state lives in memory. The server is stateless across restarts.

Development

# Clone and install
git clone https://github.com/tumourlove/unreal-editor-mcp.git
cd unreal-editor-mcp
uv sync

# Run tests (57 tests)
uv run pytest -v

# Run locally
UE_PROJECT_PATH="/path/to/project" uv run python -m unreal_editor_mcp

Adding to Your Project's CLAUDE.md

If your UE project has a CLAUDE.md (used by Claude Code for project context), add a note so the AI knows build and log tools are available:

## MCP Servers

- **unreal-editor-mcp** is configured. Use `trigger_build` to compile via Live Coding,
  `get_build_errors` to inspect failures, and `get_recent_logs` / `search_logs` to
  check editor output. Always check build results after modifying C++ code.

Requirements

• Python 3.11+
• uv (recommended) or pip
• Unreal Engine 5.x with Python plugin and Remote Execution enabled

License

MIT