Mason MCP is a native Model Context Protocol server built into the Unreal Editor. Connect Claude Code, Claude Desktop, Cursor, Windsurf, Cline, VS Code Copilot, Codex CLI, Gemini CLI, Cherry Studio or any MCP-capable AI and drive 533 editor operations across 60 categories (advertised to your AI as 270 aggregated tool entries — ~85% less context) with natural language — no boilerplate Python, no leaving the engine.

HEADLINE FEATURE — THE AI PERFORMANCE OPTIMIZER: one call measures your scene, audits assets, and returns a prioritized report where every recommendation is a runnable tool call. Measure → audit → report → apply → re-measure, in-editor.

WHAT YOUR AI CAN DO: author Blueprints and AnimGraphs · build materials and lighting (golden hour in one prompt) · wire Sequencer cutscenes with cine cameras · generate PCG scatter and Geometry Script meshes · control World Partition, Landscape, Foliage, MetaHuman, Control Rig, Niagara, audio, localization, networking · run automated tests · profile performance.

WHY MASON MCP: a real C++ HTTP JSON-RPC 2.0 server (MCP 2025-06-18) inside the editor — not a fragile wrapper. Aggregated catalog + schema-on-demand: tools/list costs ~1.2–1.7K tokens instead of ~11.3K. MCP Resources, Prompts, SSE and CORS built in; a stdio Python bridge covers clients that need it.

SAFETY YOU CAN TRUST: every operation is safety-scoped 🟢 read (~36%) / 🟡 scene (~59%) / 🔴 destructive (~5%), enforced server-side before any handler runs. Loopback-only by default (TCP 55557, HTTP 55558), optional Bearer-token auth, request rate-limiting, preset tool-sets (minimal / scene / gameplay / full). Python execution requires explicit opt-in.

EXTENSIBLE: other plugins register their own MCP tools through a public extension point (FMCPExternalCommandRegistry) — Mason MCP depends only on the engine.

INCLUDES: full C++ source (Fab code plugin), Python stdio bridge + ready-to-paste configs for 9 AI clients, bilingual docs (TOOLS.md catalog, CLIENT_SETUP.md, PERF_LOOP_GUIDE.md), community & support on Discord.

COMPATIBILITY: Unreal Engine 5.3–5.8 · editor-only · Win64 · 60 fps capture demo: https://youtu.be/Rnu6cmAWUyg

Mason MCP declares the following Unreal Engine plugins as compile-time dependencies (enabled via its `.uplugin`): EditorScriptingUtilities, DataValidation, GameplayAbilities, EnhancedInput, LevelSequenceEditor, Niagara, CommonUI, PCG, GeometryScripting, IKRig, plus optional ChaosEditor, GeometryCollectionPlugin, Fracture, PlanarCut, MetaSound, StateTree. All are Epic-shipped engine plugins; Mason MCP adds no third-party runtime dependencies.

Watch the 90-second demo: https://youtu.be/Rnu6cmAWUyg

Documentation: https://github.com/MasonCraftGames/MasonMCP-docs

Support & community (verify purchase with /verify): https://discord.gg/uD9px9vbpz

Support: [email protected]