NAME
soft-ue-cli — Python CLI + UE plugin that lets Claude Code (AI coding agent) control Unreal Engine in real time. Spawn actors, edit…
SYNOPSIS
pip install soft-ue-cliINFO
DESCRIPTION
Python CLI + UE plugin that lets Claude Code (AI coding agent) control Unreal Engine in real time. Spawn actors, edit blueprints, call functions, capture screenshots, manage PIE sessions, and more -- all from the terminal. Works with UE5 editor and packaged builds via an in-process HTTP bridge.
README
soft-ue-cli (+mcp)
Built and maintained by a solo developer. Support this project if it saves you time.
Control Unreal Engine 5 from your AI agent or terminal. soft-ue-cli gives any LLM — via MCP server or CLI — 60+ tools to spawn actors, edit Blueprints, inspect materials, read and patch UE config files, run Play-In-Editor sessions, capture screenshots, profile performance, and more inside a running UE5 editor or packaged build.
Two ways to connect. Same 60+ tools. One pip install. One plugin copy.
Why soft-ue-cli?
- MCP server + CLI in one package -- use as an MCP server (
mcp-serve) for Claude Desktop, Cursor, Windsurf, and other MCP clients, or as a standard CLI for Claude Code, shell scripts, and CI/CD. Same 60+ tools either way. - AI-native UE automation -- purpose-built so LLM agents can read, modify, and test Unreal Engine projects without a human touching the editor.
- 60+ tools covering actors, Blueprints, materials, StateTrees, widgets, assets, config files, PIE sessions, profiling, and more.
- Config-aware workflows — inspect hierarchy, trace overrides, diff layers, and patch
.ini,BuildConfiguration.xml, and.uprojectdata from oneconfigcommand group. - LLM skill prompts -- ships with markdown workflows (e.g. Blueprint-to-C++ conversion) exposed as MCP prompts or CLI commands.
- Works everywhere UE runs -- editor, cooked builds, Windows, macOS, Linux.
- Single dependency -- only requires
httpx. Add[mcp]extra for MCP server mode. - Team-friendly -- conditional compilation via
SOFT_UE_BRIDGEenvironment variable means only developers who need the bridge get it compiled in.
Quick Start
1. Install
pip install soft-ue-cli # CLI only
pip install soft-ue-cli[mcp] # CLI + MCP server
2. Install the plugin into your UE project
Run the setup command inside your LLM client (Claude Code, Cursor, etc.) — it outputs step-by-step instructions that the AI agent will follow to copy the plugin, edit your .uproject, and configure itself:
soft-ue-cli setup /path/to/YourProject
If you're running manually (not via an LLM), follow the printed instructions yourself: copy the plugin directory, add the "Plugins" entry to your .uproject, and create the CLAUDE.md snippet.
3. Rebuild and launch Unreal Engine
After regenerating project files and rebuilding, launch the editor. Look for this log line to confirm the bridge is running:
LogSoftUEBridge: Bridge server started on port 8080
5. Verify the connection
soft-ue-cli check-setup
You should see all checks pass:
[OK] Plugin files found.
[OK] SoftUEBridge enabled in YourGame.uproject.
[OK] Bridge server reachable.
5. (Optional) Connect your MCP client
Add to your MCP client config (Claude Desktop, Cursor, Windsurf, etc.):
{
"mcpServers": {
"soft-ue-cli": {
"command": "soft-ue-cli",
"args": ["mcp-serve"]
}
}
}
The AI editor now has direct access to all 60+ UE tools and skill prompts — no terminal needed.
How It Works
Claude Code
|
| (runs CLI commands in terminal)
v
soft-ue-cli (Python process)
|
| HTTP / JSON-RPC requests
v
SoftUEBridge plugin (C++ UGameInstanceSubsystem, inside UE process)
|
| Native UE API calls on the game thread
v
Unreal Engine 5 editor or runtime
The SoftUEBridge plugin is a lightweight C++ UGameInstanceSubsystem that starts an embedded HTTP server on port 8080 when UE launches. The CLI sends JSON-RPC requests to this server, and the plugin executes the corresponding UE operations on the game thread, returning structured JSON responses.
All commands output JSON to stdout (except get-logs --raw). Exit code 0 means success, 1 means error.
Skills Architecture
LLM client (Claude Code, Cursor, etc.)
|
| soft-ue-cli skills get <name>
v
Skill file (markdown shipped with CLI pip package)
|
| LLM reads instructions, type mappings, pre-filled commands
v
LLM executes soft-ue-cli commands (query-blueprint, query-blueprint-graph, ...)
|
v
LLM generates output (e.g. .h/.cpp files) following the skill's rules
Skills are markdown files at cli/soft_ue_cli/skills/*.md, shipped as package data in the pip distribution. Each skill is self-contained: workflow instructions, reference tables, example CLI commands, and verification test cases. The CLI discovers them via skills list / skills get. When running as an MCP server, the same files are exposed via the prompts/list and prompts/get protocol.
MCP Server Architecture
MCP Client (Claude Desktop, Cursor, Windsurf, etc.)
|
| stdio (JSON-RPC, MCP protocol)
v
soft-ue-cli mcp-serve (FastMCP server)
|
| Reuses call_tool() — HTTP/JSON-RPC
v
SoftUEBridge plugin (inside UE)
Running soft-ue-cli mcp-serve starts an MCP server over stdio. It auto-generates MCP tool schemas from the CLI's argparse parser and forwards tool calls to the UE bridge. Skills are exposed as MCP prompts. Install the optional extra: pip install soft-ue-cli[mcp].
Complete Command Reference
Every command is available via soft-ue-cli <command>. Run soft-ue-cli <command> --help for detailed options.
Setup and Diagnostics
| Command | Description |
|---|---|
setup | Copy SoftUEBridge plugin into a UE project |
check-setup | Verify plugin files, .uproject settings, and bridge server reachability |
status | Health check -- returns server status |
project-info | Get project name, engine version, target platforms, and module info |
Actor and Level Operations
| Command | Description |
|---|---|
spawn-actor | Spawn an actor by class at a given location and rotation |
query-level | List actors in the current level with transforms, filtering by class or name |
call-function | Call any BlueprintCallable UFUNCTION on an actor |
set-property | Set a UPROPERTY value on an actor by name |
get-property | Read a UPROPERTY value from an actor or component using reflection |
add-component | Add a component to an existing actor |
Blueprint Inspection and Editing
| Command | Description |
|---|---|
query-blueprint | Inspect a Blueprint asset -- components, variables, functions, interfaces, event dispatchers |
query-blueprint-graph | Inspect event graphs, function graphs, and node connections |
inspect-uasset | Inspect a local Blueprint .uasset file offline without a running editor |
diff-uasset | Diff two local Blueprint .uasset files offline by extracted metadata |
add-graph-node | Add a node to a Blueprint or Material graph (supports AnimLayerFunction for ALIs) |
modify-interface | Add or remove an implemented interface on a Blueprint or AnimBlueprint |
remove-graph-node | Remove a node from a graph |
connect-graph-pins | Connect two pins between graph nodes |
disconnect-graph-pin | Disconnect pin connections (all or specific with --target-node/--target-pin) |
insert-graph-node | Atomically insert a node between two connected nodes |
set-node-position | Batch-set node positions for graph layout |
compile-blueprint | Compile a Blueprint or AnimBlueprint and return the result |
compile-material | Compile a Material, MaterialInstance, or MaterialFunction |
save-asset | Save a modified asset to disk (with optional --checkout for source control) |
set-node-property | Set properties on a graph node by GUID (UPROPERTY, inner structs, pin defaults) |
Asset Management
| Command | Description |
|---|---|
query-asset | Search the Content Browser by name, class, or path -- also inspect DataTables |
create-asset | Create new Blueprint, Material, DataTable, World (Level), or other asset types |
delete-asset | Delete an asset |
set-asset-property | Set a property on a Blueprint CDO or component |
get-asset-diff | Get property-level diff of an asset vs. source control |
get-asset-preview | Get a thumbnail/preview image of an asset |
open-asset | Open an asset in the editor |
find-references | Find assets, variables, or functions referencing a given asset |
Material Inspection
| Command | Description |
|---|---|
query-material | Inspect Material, Material Instance, or Material Function -- parameters, nodes, connections, --parent-chain |
query-mpc | Read or write Material Parameter Collection scalar/vector values |
Class and Type Inspection
| Command | Description |
|---|---|
class-hierarchy | Inspect class inheritance chains -- ancestors, descendants, or both |
Play-In-Editor (PIE) Control
| Command | Description |
|---|---|
pie-session | Start, stop, pause, resume PIE -- also query actor state during play |
trigger-input | Send input events to a running game (PIE or packaged build) |
Screenshot and Visual Capture
| Command | Description |
|---|---|
capture-screenshot | Capture the editor viewport, PIE window, or a specific editor panel |
capture-viewport | Capture the current viewport (auto-detects PIE, standalone, or editor) |
set-viewport-camera | Set editor viewport camera position, rotation, or preset view (top/front/right/perspective) |
Logging and Console Variables
| Command | Description |
|---|---|
get-logs | Read the UE output log with optional category and text filters |
get-console-var | Read the value of a console variable (CVar) |
set-console-var | Set a console variable value |
Python Scripting in UE
| Command | Description |
|---|---|
run-python-script | Execute a Python script inside UE's embedded Python interpreter |
save-script | Save a reusable Python script to the local script library |
list-scripts | List all saved Python scripts |
delete-script | Delete a saved script |
StateTree Editing
| Command | Description |
|---|---|
query-statetree | Inspect a StateTree asset -- states, tasks, transitions |
add-statetree-state | Add a state to a StateTree |
add-statetree-task | Add a task to a StateTree state |
add-statetree-transition | Add a transition between StateTree states |
remove-statetree-state | Remove a state from a StateTree |
Widget Blueprint Inspection
| Command | Description |
|---|---|
inspect-widget-blueprint | Inspect UMG Widget Blueprint hierarchy, bindings, and properties |
inspect-runtime-widgets | Inspect live UMG widget geometry during PIE sessions |
add-widget | Add a widget to a Widget Blueprint |
DataTable Editing
| Command | Description |
|---|---|
add-datatable-row | Add or update a row in a DataTable asset |
Performance Profiling (UE Insights)
| Command | Description |
|---|---|
insights-capture | Start or stop a UE Insights trace capture |
insights-list-traces | List available trace files |
insights-analyze | Analyze a trace file for CPU, GPU, or memory hotspots |
Build and Live Coding
| Command | Description |
|---|---|
build-and-relaunch | Trigger a full C++ rebuild and optionally relaunch the editor (--wait to monitor progress) |
trigger-live-coding | Trigger a Live Coding compile (hot reload); waits for result by default |
Skills (LLM Workflow Prompts)
| Command | Description |
|---|---|
skills list | List all available LLM skill prompts shipped with the CLI |
skills get <name> | Print a skill's full content to stdout for LLM consumption |
Skills are markdown prompts that teach an LLM client how to perform complex multi-step workflows using soft-ue-cli commands. They include step-by-step instructions, type mapping tables, and pre-filled CLI commands.
Available skills:
| Skill | Description |
|---|---|
blueprint-to-cpp | Generate C++ .h/.cpp from a Blueprint asset -- Layer 1 (class scaffolding) + Layer 2 (graph logic translation) |
inspect-uasset | Inspect a local Blueprint .uasset offline and extract conservative metadata without launching Unreal Editor |
level-from-image | Populate a UE level from a reference image -- analyzes the image, maps scene elements to project assets, batch-places actors, then iterates with visual feedback (viewport screenshots) |
test-tools | Run the exhaustive live integration test script across CLI and MCP modes, including offline .uasset smoke checks against a generated Blueprint |
MCP Server Mode
| Command | Description |
|---|---|
mcp-serve | Run as an MCP (Model Context Protocol) server over stdio |
Exposes all 60+ commands as MCP tools and skills as MCP prompts. Compatible with Claude Desktop, Claude Code, Cursor, Windsurf, and other MCP clients. Requires the optional mcp extra:
pip install soft-ue-cli[mcp]
Usage Examples
Spawn an actor at a specific location
soft-ue-cli spawn-actor BP_Enemy --location 100,200,50 --rotation 0,90,0
Query all actors of a specific class
soft-ue-cli query-level --class-filter StaticMeshActor --limit 50
Call a BlueprintCallable function
soft-ue-cli call-function BP_GameMode SetDifficulty --args '{"Level": 3}'
Inspect a Blueprint's components and variables
soft-ue-cli query-blueprint /Game/Blueprints/BP_Player --include components,variables
Inspect and diff Blueprint .uasset files offline
soft-ue-cli inspect-uasset D:/Project/Content/Blueprints/BP_Player.uasset --sections all
soft-ue-cli diff-uasset D:/snapshots/BP_Player_before.uasset D:/Project/Content/Blueprints/BP_Player.uasset --sections variables,functions
Start a PIE session and send input
soft-ue-cli pie-session start --mode SelectedViewport
soft-ue-cli trigger-input key --key SpaceBar
soft-ue-cli pie-session stop
Capture a screenshot of the editor viewport
soft-ue-cli capture-screenshot viewport --output screenshot.png
Edit a Blueprint graph programmatically
soft-ue-cli add-graph-node /Game/BP_Player K2Node_CallFunction \
--properties '{"FunctionReference": {"MemberName": "PrintString"}}'
soft-ue-cli connect-graph-pins /Game/BP_Player node1 "exec" node2 "execute"
Manage Blueprint interfaces
soft-ue-cli modify-interface /Game/ABP_Character add ALI_Locomotion
soft-ue-cli modify-interface /Game/ABP_Character remove ALI_Locomotion
soft-ue-cli query-blueprint /Game/ABP_Character --include interfaces
Create an anim layer function on an AnimLayerInterface
soft-ue-cli add-graph-node /Game/ALI_Locomotion AnimLayerFunction --graph-name FullBody
Insert a node between two connected nodes
soft-ue-cli insert-graph-node /Game/ABP_Hero AnimGraphNode_LinkedAnimLayer \
{source-guid} OutputPose {target-guid} InputPose --graph-name AnimGraph
Save and compile after edits
soft-ue-cli compile-blueprint /Game/ABP_Hero
soft-ue-cli save-asset /Game/ABP_Hero
Disconnect a specific wire (preserving others)
soft-ue-cli disconnect-graph-pin /Game/ABP_Hero {node-guid} OutputPose \
--target-node {other-guid} --target-pin InputPose
Convert a Blueprint to C++ using the LLM skill
# List available skills soft-ue-cli skills listFeed the blueprint-to-cpp skill to your LLM client
soft-ue-cli skills get blueprint-to-cpp
The LLM reads the skill instructions, then runs:
soft-ue-cli query-blueprint /Game/BP_Player --include all --include-inherited
soft-ue-cli query-blueprint-graph /Game/BP_Player --list-callables
...and generates the .h/.cpp files from the JSON responses
Populate a level from a reference image
# Get the level-from-image skill instructions
soft-ue-cli skills get level-from-image
# The LLM analyzes the image, searches for matching assets, places them,
# then enters a visual feedback loop:
# soft-ue-cli set-viewport-camera --preset top --ortho-width 8000
# soft-ue-cli capture-viewport --source editor --output file
# Compares screenshot to reference, auto-corrects, then asks for human feedback
Profile with UE Insights
soft-ue-cli insights-capture start --channels CPU,GPU
# ... run your scenario ...
soft-ue-cli insights-capture stop
soft-ue-cli insights-analyze latest --analysis-type cpu
Use as an MCP server (Claude Desktop, Cursor, etc.)
# Install with MCP support pip install soft-ue-cli[mcp]Run the MCP server (used in MCP client config, not run manually)
soft-ue-cli mcp-serve
Add to your MCP client config (e.g. claude_desktop_config.json):
{
"mcpServers": {
"soft-ue-cli": {
"command": "soft-ue-cli",
"args": ["mcp-serve"]
}
}
}
Configuration
Environment Variables
| Variable | Default | Description |
|---|---|---|
SOFT_UE_BRIDGE_URL | (none) | Full bridge URL override (e.g. http://192.168.1.10:8080) |
SOFT_UE_BRIDGE_PORT | 8080 | Port override when using localhost |
SOFT_UE_BRIDGE | (none) | Set to 1 to enable conditional compilation in Target.cs |
Server Discovery Order
The CLI finds the bridge server using this priority:
--servercommand-line flagSOFT_UE_BRIDGE_URLenvironment variableSOFT_UE_BRIDGE_PORTenvironment variable (constructshttp://127.0.0.1:<port>).soft-ue-bridge/instance.jsonfile (searched upward from the current working directory -- written automatically by the plugin at startup)http://127.0.0.1:8080(default fallback)
Conditional Compilation for Teams
If you want only specific developers to compile the bridge plugin (to avoid any overhead for artists or designers), use the SOFT_UE_BRIDGE environment variable in your Target.cs:
// MyGameEditor.Target.cs
if (Environment.GetEnvironmentVariable("SOFT_UE_BRIDGE") == "1")
{
ExtraModuleNames.Add("SoftUEBridge");
}
Developers who need the bridge set SOFT_UE_BRIDGE=1 in their environment. Everyone else builds without it.
Compatibility
| Requirement | Supported Versions |
|---|---|
| Unreal Engine | 5.7 |
| Python | 3.10+ |
| Platforms | Windows, macOS, Linux |
| Build types | Editor, Development, Shipping (cooked/packaged) |
| Dependencies | httpx >= 0.27 (sole runtime dependency); optional mcp >= 1.2 for MCP server mode |
Development
git clone https://github.com/softdaddy-o/soft-ue-cli
cd soft-ue-cli
pip install -e .
pytest -v
Feedback
Report a bug
soft-ue-cli report-bug \
--title "Short bug summary" \
--description "Detailed description"
Optional flags: --steps, --expected, --actual, --severity critical|major|minor, --no-system-info.
Request a feature
soft-ue-cli request-feature \
--title "Short feature summary" \
--description "What the feature should do"
Optional flags: --use-case, --priority enhancement|nice-to-have.
Share a testimonial
soft-ue-cli submit-testimonial \
--message "Great tool for UE automation!" \
--agent-name "Claude Code" \
--rating 5
Opens a GitHub Issue (label: testimonial) with auto-collected metadata (CLI version, usage streak, top tools). A consent prompt appears before posting unless --yes is passed.
All feedback commands require GitHub auth: set GITHUB_TOKEN env var or run gh auth login.
Frequently Asked Questions
What is soft-ue-cli?
soft-ue-cli is a Python tool that gives AI agents and developers 60+ operations to control Unreal Engine 5. It works as an MCP server (for Claude Desktop, Cursor, Windsurf, and other MCP clients) or as a standard CLI (for Claude Code, shell scripts, CI/CD). It communicates with a C++ plugin (SoftUEBridge) running inside UE via HTTP/JSON-RPC, enabling actor spawning, Blueprint editing, material inspection, Play-In-Editor sessions, screenshot capture, performance profiling, and more.
How do AI agents use soft-ue-cli?
MCP clients (Claude Desktop, Cursor, Windsurf): Connect via soft-ue-cli mcp-serve. The agent sees all 60+ tools with typed schemas and skill prompts — it can directly call UE operations without going through a terminal.
Claude Code: Runs soft-ue-cli commands in the terminal. Add a CLAUDE.md file to your UE project describing available commands, and Claude Code autonomously queries your level, spawns actors, edits Blueprints, runs PIE sessions, and iterates on your game.
Can I use soft-ue-cli without an AI agent?
Yes. soft-ue-cli is a standard Python CLI. You can use it in shell scripts, CI/CD pipelines, custom automation tools, or any workflow that can invoke command-line programs. Every command outputs structured JSON, making it easy to parse and integrate.
Does it work with packaged/cooked Unreal Engine builds?
Yes. The SoftUEBridge plugin works in both the UE editor and in cooked/packaged builds (Development and Shipping configurations). This makes it useful for automated testing of packaged games.
What Unreal Engine versions are supported?
soft-ue-cli is actively developed against Unreal Engine 5.7.
Is there any runtime performance impact?
The SoftUEBridge plugin adds a lightweight HTTP server that listens on a single port. When no requests are being made, the overhead is negligible. The server processes requests on the game thread to ensure thread safety with UE APIs. For production builds where you do not want the bridge, use conditional compilation via the SOFT_UE_BRIDGE environment variable.
How do I change the default port?
Set the SOFT_UE_BRIDGE_PORT environment variable before launching UE, or use the --server flag when running CLI commands. The default port is 8080.
Can multiple UE instances run simultaneously?
Yes. Each UE instance writes its port to a .soft-ue-bridge/instance.json file in the project directory. Use SOFT_UE_BRIDGE_URL or --server to target a specific instance when multiple are running.
How do I edit Blueprints from the command line?
Use query-blueprint-graph to inspect existing graph nodes, add-graph-node to create new nodes, connect-graph-pins to wire them together, and remove-graph-node to delete nodes. This enables fully programmatic Blueprint construction -- useful for AI-driven development and automated testing.
What is the difference between soft-ue-cli and Unreal Engine Remote Control?
Unreal Engine's built-in Remote Control API focuses on property access and preset-based workflows. soft-ue-cli provides a broader command set specifically designed for AI coding agents -- including Blueprint graph editing, StateTree manipulation, PIE session control, UE Insights profiling, widget inspection, and asset creation -- with a simpler setup process (one pip install, one plugin copy).
How do I use soft-ue-cli with Claude Desktop or Cursor?
Run pip install soft-ue-cli[mcp] to install MCP support, then add the server to your MCP client config. For Claude Desktop, add to claude_desktop_config.json:
{
"mcpServers": {
"soft-ue-cli": {
"command": "soft-ue-cli",
"args": ["mcp-serve"]
}
}
}
The MCP server exposes all 60+ commands as MCP tools and skills as MCP prompts. The AI editor can then directly call UE operations without going through the terminal.
What is the difference between soft-ue-cli and other UE MCP servers?
| soft-ue-cli | unreal-mcp, ue5-mcp, etc. | |
|---|---|---|
| Tools | 60+ | 10–49 |
| Coverage | Blueprints, materials, StateTrees, widgets, PIE, profiling, DataTables, CVars, Live Coding | Varies; most cover actors + basic assets |
| LLM skill prompts | Yes (MCP prompts + CLI) | No |
| CLI mode | Yes — shell scripts, CI/CD, Claude Code | MCP-only |
| Setup | pip install soft-ue-cli[mcp] + copy one plugin | Varies; often requires custom C++/Python scripting |
Support this project
soft-ue-cli is free, open-source, and maintained by one person. If it saves you hours of manual editor work or helps your AI workflow, consider supporting continued development:
- Sponsor on GitHub — recurring or one-time
- Buy me a coffee on Ko-fi — quick one-time donation
Using soft-ue-cli in your project? Share your experience — I'd love to hear about it.
Roadmap
- UE 5.8 support
- More LLM skills (Material-to-HLSL, Animation Blueprint automation)
- Visual diff for Blueprint changes
- CI/CD integration examples
License
MIT License. See LICENSE for details.
Links
- PyPI: pypi.org/project/soft-ue-cli
- GitHub: github.com/softdaddy-o/soft-ue-cli
- Claude Code: docs.anthropic.com/en/docs/claude-code