Unreal-MCP-Ghost

Unreal-MCP-Ghost is an Unreal Engine 5.6 editor plugin plus a Python FastMCP server that lets AI agents inspect and modify live UE projects through the Model Context Protocol.

The current server registers 713 MCP tools. The plugin exposes a TCP bridge to Unreal Editor on port 55655, and the Python server exposes MCP over stdio, sse, or streamable-http. The plugin also includes an optional dockable MCP Chat editor window with a compact IDE cockpit overview, queued-action preview, evidence timeline and artifact preview, live context chips, typed drag/drop references, and a categorized tool palette that can send messages to Cursor through the server.

main is the stable public branch. Experimental work belongs on wip. Project-specific knowledge, generated reports, and development logs remain local and are excluded from the public repository.

What It Can Do

• Inspect levels, actors, Blueprints, components, variables, graphs, nodes, pins, compile diagnostics, references, source control state, and project assets.

• Create and edit Blueprints, Blueprint Interfaces, variables, functions, graph nodes, comments, connections, timers, input handlers, UMG widgets, materials, data assets, save-game systems, and gameplay framework classes.

• Work with AI systems: Behavior Trees, Blackboards, AI Controllers, BT tasks/decorators/services, navmesh helpers, and higher-level AI setup workflows.

• Work with animation systems: Animation Blueprints, state machines, blend spaces, AnimGraph slot insertion, Control Rig asset/control/constraint helpers, IK Rig creation, IK Retargeter creation, skeleton bone inspection, and batch retargeting.

• Import assets: textures, static meshes, skeletal meshes, audio, folders, and KotOR/GhostRigger assets.

• Add VFX/audio/material logic: Niagara components, spawn Niagara nodes, sound nodes, material instance parameters, collision settings, and Sequencer transform tracks.

• Validate and repair Blueprints with diagnostic, repair, execution journal, action risk-evaluation, PIE, log, and viewport evidence tools.

• Provide a repo knowledge base for UE5 workflows, Blueprint patterns, MCP usage, first-person systems, retargeting, Sequencer, Control Rig, weapons, melee, force powers, and boss AI.

• Provide an editor-side chat panel with a compact IDE cockpit overview, queued-action preview, evidence timeline and artifact preview, live level, actor, dirty-asset, compile, and SSE server context chips, typed asset/actor/file drag-drop references, a categorized tool palette, and an optional Cursor SDK watcher for automatic replies.

Related MCP server: unreal-engine-mcp

Architecture

AI client or Cursor watcher
  |
  | MCP stdio / SSE / streamable-http
  v
Python FastMCP server
  - unreal_mcp_server/unreal_mcp_server.py
  - 713 registered MCP tools
  - optional /chat/* HTTP routes on port 8000
  |
  | TCP JSON, one command per connection
  v
UnrealMCP UE plugin
  - localhost:55655
  - runs commands on the editor GameThread
  - UnrealMCP module: TCP bridge and command handlers
  - UnrealMCPEditor module: Window > MCP Chat
  |
  v
Unreal Engine Editor

Repository Layout

Unreal-MCP-Ghost/
|-- unreal_plugin/                 # UE5 editor plugin to copy into a project
|-- unreal_mcp_server/             # Python FastMCP server and tool modules
|-- knowledge_base/                # General Unreal/MCP reference docs
|-- docs/knowledge-base/           # Packt study guides used by agents
|-- scripts/ue-chat-agent.mjs      # Optional Cursor SDK chat watcher
|-- docs/ue-editor-chat-agent.md   # Chat watcher instructions
|-- package.json                   # Node dependency for chat watcher
`-- pyproject.toml                 # Python dependency metadata

First-Time Setup

1. Install Prerequisites

• Unreal Engine 5.6

• Visual Studio 2022 with Game development with C++

• Python 3.10+

• Git

• Node.js 20+ if you want automatic editor chat replies

• uv is recommended for Python dependency/running workflows

Check basics:

python --version
uv --version
node --version
git --version

2. Clone the Repo

git clone https://github.com/CrispyW0nton/Unreal-MCP-Ghost.git "C:\Dev\Unreal-MCP-Ghost"
cd "C:\Dev\Unreal-MCP-Ghost"

3. Copy the Plugin into Your UE Project

The plugin must live under your project's Plugins folder.

$REPO    = "C:\Dev\Unreal-MCP-Ghost"
$PROJECT = "C:\Users\You\Documents\UnrealProjects\MyGame"

New-Item -ItemType Directory -Force -Path "$PROJECT\Plugins\UnrealMCP"
Copy-Item -Recurse -Force "$REPO\unreal_plugin\*" "$PROJECT\Plugins\UnrealMCP\"

When updating an existing project plugin, close Unreal Editor first and remove old plugin build artifacts:

Stop-Process -Name UnrealEditor -Force -ErrorAction SilentlyContinue
Remove-Item -Recurse -Force "$PROJECT\Plugins\UnrealMCP\Binaries" -ErrorAction SilentlyContinue
Remove-Item -Recurse -Force "$PROJECT\Plugins\UnrealMCP\Intermediate" -ErrorAction SilentlyContinue
Copy-Item -Recurse -Force "$REPO\unreal_plugin\*" "$PROJECT\Plugins\UnrealMCP\"

4. Generate Project Files

Right-click your .uproject and choose Generate Visual Studio project files, or run:

$UPROJECT = "$PROJECT\MyGame.uproject"
& "C:\Program Files\Epic Games\UE_5.6\Engine\Build\BatchFiles\GenerateProjectFiles.bat" `
  -project="$UPROJECT" -game -rocket

5. Build the Plugin

Open the generated .sln in Visual Studio 2022:

• Configuration: Development Editor

• Platform: Win64

• Build: Ctrl+Shift+B

Or build from PowerShell:

& "C:\Program Files\Epic Games\UE_5.6\Engine\Build\BatchFiles\Build.bat" `
  MyGameEditor Win64 Development `
  -Project="$UPROJECT" `
  -WaitMutex -FromMsBuild -architecture=x64

Expected result:

Result: Succeeded

Notes:

• Visual Studio 2022 compiler is not a preferred version is usually a warning, not a blocker.

• If build fails with exit code 6, scroll up for the actual error C... compiler line.

• If Live Coding is active, close Unreal Editor or press Ctrl+Alt+F11.

6. Open Unreal and Verify the Plugin

Open the .uproject. In Window > Output Log, confirm:

UnrealMCPBridge: Server started on 127.0.0.1:55655

PowerShell port check:

python -c "import socket; s=socket.socket(); s.settimeout(2); r=s.connect_ex(('127.0.0.1',55655)); s.close(); print('PLUGIN RUNNING' if r==0 else 'PLUGIN NOT RUNNING')"

Running the MCP Server

Local AI Clients: stdio

Use this when Cursor, Claude Desktop, Windsurf, or another local MCP client launches the server itself:

{
  "mcpServers": {
    "unrealMCP": {
      "command": "uv",
      "args": [
        "--directory",
        "C:\\Dev\\Unreal-MCP-Ghost",
        "run",
        "python",
        "unreal_mcp_server\\unreal_mcp_server.py"
      ]
    }
  }
}

If you do not use uv:

{
  "mcpServers": {
    "unrealMCP": {
      "command": "python",
      "args": ["C:\\Dev\\Unreal-MCP-Ghost\\unreal_mcp_server\\unreal_mcp_server.py"]
    }
  }
}

Restart the AI client after editing MCP config.

HTTP/SSE Server

Use this when remote clients, Cursor SDK processes, or the Unreal editor chat panel need HTTP routes:

cd "C:\Dev\Unreal-MCP-Ghost"
python unreal_mcp_server\unreal_mcp_server.py --transport sse --mcp-host 127.0.0.1 --mcp-port 8000

Expected:

[UnrealMCP] SSE server listening on http://127.0.0.1:8000/sse
[UnrealMCP] UE5 plugin target: 127.0.0.1:55655

The HTTP chat routes do not provide application-layer authentication, so the server only accepts loopback binds. For remote access, keep this loopback bind and put an authenticated tunnel or reverse proxy in front of it.

Quick HTTP checks:

Invoke-RestMethod "http://127.0.0.1:8000/chat/history?limit=1"

Streamable HTTP

For MCP clients supporting the newer streamable HTTP transport:

python unreal_mcp_server\unreal_mcp_server.py --transport streamable-http --mcp-host 127.0.0.1 --mcp-port 8000

Endpoint: http://127.0.0.1:8000/mcp

Unreal Editor Chat

The plugin registers a dockable tab:

Window > MCP Chat

The tab is implemented in the editor-only UnrealMCPEditor module so the core UnrealMCP module can stay focused on TCP bridge command handling.

The panel:

• Loads previous messages from /chat/history

• Sends human messages to /chat/send

• Polls agent replies from /chat/poll?sender=agent

• Uses a resizable conversation/composer split with multiline input, drag/drop reference insertion, and Enter-to-send / Shift+Enter newline behavior

• Renders role-tagged user, agent, and tool message bubbles with Copy, Re-run, Open Log, and Reveal Asset actions

• Renders structured MCP tool invocations as collapsible cards with args, status, result summaries, full-detail drawer, log tail, and a Repair action for failed tool results

• Renders fenced Markdown code blocks as highlighted monospaced blocks and updates streaming data: deltas in place when available

• Includes editor context such as current level and selected actor

• Shows connection status against http://127.0.0.1:8000

Start the MCP server in SSE mode before opening the chat panel:

python unreal_mcp_server\unreal_mcp_server.py --transport sse --mcp-host 127.0.0.1 --mcp-port 8000

Automatic Cursor Replies

The editor chat window is a message bridge. To make Cursor answer automatically, run the watcher in a separate terminal:

cd "C:\Dev\Unreal-MCP-Ghost"
npm install
$env:CURSOR_API_KEY = "cursor_..."
npm run chat:agent

Useful options:

$env:UE_CHAT_SERVER_URL = "http://127.0.0.1:8000"
$env:UE_CHAT_POLL_INTERVAL_MS = "2000"
$env:UE_CHAT_CATCH_UP = "1"
$env:UE_CHAT_SESSION = "My Session"
$env:CURSOR_MODEL = "auto"

More detail: docs/ue-editor-chat-agent.md.

Knowledge Base

Agents should read repository knowledge before making Unreal changes:

• docs/knowledge-base/README.md

• docs/knowledge-base/unreal-cpp-li-2023.md

• docs/knowledge-base/elevating-game-experiences-ue5-2e.md

• docs/knowledge-base/game-ai-unreal-sapio-2019.md

• knowledge_base/

Current Tool Surface

The server currently registers 713 MCP tools, including:

• Core editor/actor tools

• Blueprint creation, graph editing, node connection, variable/function tools

• UMG/widget tools

• Gameplay framework tools

• AI, Behavior Tree, Blackboard, BT task/decorator/service tools

• Animation Blueprint, IK Rig, IK Retargeter, skeleton, and batch retargeting tools

• Data, struct, enum, DataTable, save-game, input, and Enhanced Input tools

• Material, VFX, Niagara, audio, physics, math, trace, procedural, VR, and variant tools

• Asset import and folder import tools

• GhostRigger bridge tools

• Safe execution substrate, execution journals, action risk evaluation, PIE/log/viewport evidence capture, reflection, diagnostics, source control, project intelligence, C++ bridge, and repair tools

• Higher-level skills such as IDE companion session orchestration/status receipts/work orders/evidence ledgers/resume packets/dashboards/blocker resolution/placeholder manifests/generated asset lifecycle manifests/editor action queues, gameplay mechanic planning, blueprint health audit, health system creation, vertical slice report packaging, and broken blueprint repair

• Chat tools: chat_poll_messages, chat_send_response, chat_get_context, chat_list_sessions, chat_get_session_resume_context, chat_get_cockpit_overview, chat_get_cockpit_ledger_detail

• Native-alignment meta-tools for toolset search, clean-room tool contribution contracts, client config generation, bridge descriptors, guarded bridge command calls, server lifecycle status, transport diagnostics, protocol contract/session guidance, operation status/cancel requests, safe metadata refresh, spatial awareness of live UE scenes, spatial room-bounds designation contracts for Ghost.RoomBounds/Ghost.Zone/Ghost.Opening/Ghost.Path/Ghost.Surface markers, live room analysis for dimensions/zones/surfaces/clearances, authored marker recognition, functional zone inference for kitchen/living/bedroom/entry/hallway/utility planning, zone-aware interior prop programming for fixtures/furniture/clutter/architectural fill, analysis-driven and support-surface-informed interior composition planning, semantic composition constraints/preflight for support contact, counter adjacency, kitchen work triangles, living groupings, circulation, hallway linear-clearance review, opening/egress clearance, entry-to-anchor visual sightlines, and per-prop front-facing interaction clearance, screenshot vision-decomposition requests, screenshot scene-graph relationship inference, size-aware live project asset cataloging and candidate resolution before Tripo spend, local screenshot crop manifests for Tripo image inputs, guarded Tripo generation batch manifests with project-asset-filtered unresolved-prop jobs and per-job prompt/spend/import/placement/validation lifecycle metadata, spatial generation briefs, concrete image-crop readiness gates, and binding handoffs that merge reused project assets plus generated imports into one dry-run composition, post-binding spatial pipeline handoffs for scale review, support anchoring, layout/candidate-clearance preflight, dry-run apply, validation, iteration, and viewport evidence, generated-asset binding from Tripo import results with spatial-fit review, generated-asset scale correction before dry-run placement, support-surface anchoring for floor/counter/table/shelf/wall contact, composition-derived support surfaces for screenshot/generated counters and tables, composition-derived room/zone wall anchors for generated wall props, dry-run-first and spatial-fit-gated composition batch application, spatial worldbuilding work orders/readiness gates with screenshot crop-manifest blockers before Tripo image-to-model spend and live candidate-clearance blockers before mutation, local layout preflight for room bounds/footprints/spacing/opening clearance/front-facing interaction clearance/visual sightlines, local layout-preflight correction planning for room-bound/overlap/circulation repair before mutation, live actor-bounds candidate clearance preflight, iterative correction planning from placement validation or live candidate-clearance blockers with corrected composition-plan handoffs, surface-aware placement probes, placement validation/evidence planning, placement policy inference, screenshot detection preflight/normalization, screenshot-driven detected-prop programming, screenshot reconstruction planning with scene-graph-guided placement hints, screenshot-detected opening/window clearance constraints, and guarded Tripo generation/import/crop handoffs, Content Browser selection handoff/batch placement, selection-aware viewport/evidence setup, and dry-run-first spatial asset placement with actor tags/Data Layer-aware planning

Use list_knowledge_base_topics, get_knowledge_base, and search_knowledge_base before implementing systems. Use get_blueprint_nodes, get_blueprint_variables, and get_blueprint_components before modifying any Blueprint.

Canonical offline inventory command:

python scripts\tool_inventory.py --markdown

The inventory uses unreal_mcp_server/tool_inventory_categories.json to map modules to roadmap categories and phases. Keep this in sync when adding new tool modules.

Phase 7 startup/tool-discovery profiler:

python scripts\profile_mcp_startup.py --iterations 3 --markdown-out knowledge_base\Reports\mcp_startup_profile.md --json-out knowledge_base\Reports\mcp_startup_profile.json

The generated report files remain local and are ignored by Git.

Phase 7 bridge command metadata audit:

python scripts\bridge_command_audit.py

For repeatable offline CI smoke commands, see docs/ci-smoke.md.

Safe Blueprint Workflow

1. Read relevant knowledge docs.

2. Inspect current state:

   • get_blueprint_nodes

   • get_blueprint_variables

   • get_blueprint_components

   • get_blueprint_graphs

3. Report findings and plan.

4. Make one scoped change.

5. Compile and save.

6. Read back and verify.

7. Keep the project playable after each change.

Never hard-code node IDs. Always query nodes after creation before connecting pins.

Troubleshooting

/chat/history or /chat/poll returns 404

You are running an old MCP server process. Stop the process listening on port 8000 and restart the current server:

Get-NetTCPConnection -LocalPort 8000 -State Listen | Select-Object OwningProcess
Stop-Process -Id <PID> -Force
python unreal_mcp_server\unreal_mcp_server.py --transport sse --mcp-host 127.0.0.1 --mcp-port 8000

Editor chat says "MCP Server offline"

• Confirm the SSE server is running on port 8000.

• Confirm /chat/history returns 200.

• Close and reopen Window > MCP Chat.

AI cannot reach Unreal

• Confirm Unreal Editor is open.

• Confirm Output Log says the bridge started on 127.0.0.1:55655.

• Confirm no firewall or tunnel is blocking the port.

• Restart the MCP server after restarting Unreal.

Build fails with Live Coding active

Close Unreal Editor or press Ctrl+Alt+F11, then rebuild.

PawnSensing deprecation warnings

The plugin suppresses the known UE 5.6 deprecation warning around legacy UPawnSensingComponent usage. New AI work should prefer AI Perception.

Updating the Plugin in a Project

From a clean repo checkout:

cd "C:\Dev\Unreal-MCP-Ghost"
git fetch origin
git status

Review local changes before updating. Then copy the plugin source into your project:

$REPO    = "C:\Dev\Unreal-MCP-Ghost"
$PROJECT = "C:\Users\You\Documents\UnrealProjects\MyGame"

Stop-Process -Name UnrealEditor -Force -ErrorAction SilentlyContinue
Remove-Item -Recurse -Force "$PROJECT\Plugins\UnrealMCP\Binaries" -ErrorAction SilentlyContinue
Remove-Item -Recurse -Force "$PROJECT\Plugins\UnrealMCP\Intermediate" -ErrorAction SilentlyContinue
Copy-Item -Recurse -Force "$REPO\unreal_plugin\*" "$PROJECT\Plugins\UnrealMCP\"

Regenerate project files and rebuild Development Editor | Win64.

License

Unreal-MCP-Ghost is licensed under the GNU Affero General Public License v3.0.

Portions of this project are derived from or inspired by chongdashu/unreal-mcp. See NOTICE.md for attribution and license details.

Security

Report security issues privately using the guidance in SECURITY.md. Do not open public issues for vulnerabilities, secrets, or exploit details.