soft-ue-cli 1.33.1

CLI tool for controlling Unreal Engine via soft-ue-bridge plugin

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 connection paths. Same package. Bridge tools when Unreal is running, offline tools when it is not.

LLM client / shell / CI
    |
    v
soft-ue-cli  (CLI or MCP server)
    |
    +-- Live bridge path ----------------------------------------------+
    |      HTTP / JSON-RPC
    |      -> SoftUEBridge plugin inside UE editor / PIE / dev build
    |      -> Actor, Blueprint, material, widget, PIE, profiling tools
    |
    +-- Offline local path --------------------------------------------+
           Direct local parsing
           -> .uasset / .uexp / .ini / .uproject / BuildConfiguration.xml
           -> inspect-uasset, diff-uasset, config tree/get/diff/audit, skills

---

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.
• Online + offline workflows -- bridge-backed UE mutation and runtime inspection when Unreal is open, plus direct local inspection, diff, and config tooling when it is not.
• Config-aware workflows — inspect hierarchy, trace overrides, diff layers, and patch .ini, BuildConfiguration.xml, and .uproject data from one config command 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_BRIDGE environment 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

soft-ue-cli command
    |
    +-- Bridge-backed commands ----------------------------------------+
    |      HTTP / JSON-RPC
    |      -> SoftUEBridge plugin (UGameInstanceSubsystem inside UE)
    |      -> UE APIs on the game thread
    |      -> Runtime/editor operations such as spawn-actor, PIE, query-level
    |
    +-- Offline commands ----------------------------------------------+
           Local parsers and file readers
           -> Package tables / tagged properties / config hierarchy
           -> inspect-uasset, diff-uasset, config *, skills get/list

The SoftUEBridge plugin is a lightweight C++ UGameInstanceSubsystem that starts an embedded HTTP server on port 8080 when UE launches. Bridge-backed commands send JSON-RPC requests to this server, and the plugin executes the corresponding UE operations on the game thread, returning structured JSON responses. Offline commands bypass the bridge entirely and operate directly on local files.

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.

Test Workflow

Use soft-ue-cli to explore and debug a gameplay bug quickly, then move the final regression into the project's C++ Automation Spec suite.

CLI + bridge + Python exploration
    -> find the signal
    -> validate the repro
    -> identify the exact assertion
    -> write the committed C++ Automation Spec in the project test module

The CLI is the exploration layer. The committed regression gate should live in project-native C++ tests rather than depending on the CLI, bridge, or Python runtime.

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].

---

Command Discovery And Taxonomy

Use soft-ue-cli commands to inspect the public command surface without connecting to Unreal:

soft-ue-cli commands
soft-ue-cli commands --json
soft-ue-cli commands --category umg
soft-ue-cli commands --category mutable
soft-ue-cli commands --category statetree
soft-ue-cli commands --plugin Mutable --json

The JSON output marks each command as canonical, compatibility, or deprecated, and includes whether it needs the bridge, editor, PIE, or optional Unreal plugins. Plugin-dependent bridge tools use a structured unavailable response when a plugin is missing:

{
  "success": false,
  "error_code": "plugin_unavailable",
  "plugin": "StateTree",
  "command": "statetree inspect",
  "recovery": "Enable the StateTree plugin, rebuild if prompted, and restart the editor."
}

UMG, capture, Mutable, StateTree, animation, asset, and Blueprint workflows now have canonical command families. Existing one-off commands remain as compatibility wrappers for this release:

Compatibility command	Canonical command
apply-widget-tree	umg designer apply
inspect-widget-blueprint	umg designer inspect
wire-widget-navigation	umg navigation wire
verify-umg-workflow	umg workflow run
extract-umg-layout	umg layout extract
compare-umg-layout	umg layout compare --mode geometry
compare-umg-screenshot	umg layout compare --mode pixel
capture-viewport	capture viewport
capture-screenshot	capture screenshot --source <mode>
capture-pie-screenshot	capture screenshot --source pie-window
inspect-customizable-object-graph	mutable inspect graph
inspect-mutable-parameters	mutable inspect parameters
inspect-mutable-diagnostics	mutable inspect diagnostics
add-co-node	mutable graph add-node
add-co-parameter	mutable graph add-parameter
add-co-mesh-option	mutable graph add-mesh-option
set-co-base-mesh	mutable graph set-base-mesh
add-co-group-child	mutable graph add-group-child
set-co-node-property	mutable graph set-node-property
connect-co-pins	mutable graph connect-pins
regenerate-co-node-pins	mutable graph regenerate-node-pins
remove-co-node	mutable graph remove-node
create-co-from-spec	mutable graph create-from-spec
wire-customizable-object-slot-from-table	mutable graph wire-slot-from-table
compile-co	mutable compile
query-statetree	statetree inspect
add-statetree-state	statetree state add
remove-statetree-state	statetree state remove
add-statetree-task	statetree task add
add-statetree-transition	statetree transition add
inspect-anim-instance	anim instance inspect
inspect-sync-markers	anim sync-marker inspect
compare-sync-markers	anim sync-marker compare
add-sync-marker	anim sync-marker add
remove-sync-marker	anim sync-marker remove
add-anim-state-machine	anim state-machine add
add-anim-state	anim state add
add-anim-transition	anim transition add
rewind-start	anim rewind start
rewind-stop	anim rewind stop
rewind-status	anim rewind status
rewind-list-tracks	anim rewind list-tracks
rewind-overview	anim rewind overview
rewind-snapshot	anim rewind snapshot
rewind-save	anim rewind save
query-asset	asset query
delete-asset	asset delete
release-asset-lock	asset release-lock
get-asset-diff	asset diff
get-asset-preview	asset preview
open-asset	asset open
set-asset-property	asset set-property
inspect-uasset	asset inspect-file
diff-uasset	asset diff-file
save-asset	asset save
create-asset	asset create
query-blueprint	blueprint inspect
query-blueprint-graph	blueprint graph inspect
compile-blueprint	blueprint compile
add-graph-node	blueprint node add
remove-graph-node	blueprint node remove
set-node-position	blueprint node position
set-node-property	blueprint node property
connect-graph-pins	blueprint pin connect
disconnect-graph-pin	blueprint pin disconnect
modify-interface	blueprint interface modify

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
wait-for-ready	Poll the same bridge health probe as status until it is ready (await-bridge alias)
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, class default object, or transient instance
batch-call	Dispatch multiple bridge tool calls in-process with one HTTP roundtrip
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
blueprint	Canonical Blueprint inspection, graph, node, pin, interface, and compile command family
query-blueprint	Inspect a Blueprint asset -- components, variables, functions, interfaces, event dispatchers
query-blueprint-graph	Inspect event graphs, function graphs, nested AnimBlueprint graphs, node connections, positions, and class-filtered nodes
inspect-uasset	Inspect a local .uasset file offline by parsed metadata, with best support for Blueprint and External Actor assets
diff-uasset	Diff two local .uasset files offline by parsed metadata, with best support for Blueprint and External Actor assets
add-graph-node	Add a node to a Blueprint or Material graph (supports AnimLayerFunction for ALIs)
add-anim-state-machine	Add an initialized AnimBlueprint state machine with optional initial state
add-anim-state	Add a state and state content graph to an AnimBlueprint state machine
add-anim-transition	Add a transition and transition rule graph between AnimBlueprint states
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
asset	Canonical asset query, preview, source-control, offline file, creation, and save command family
mutable	Canonical Mutable/CustomizableObject inspection, graph authoring, and compile command family
query-asset	Search the Content Browser by name, class, or path -- also inspect DataTables and map WorldSettings such as DefaultGameMode
query-enum	Inspect a UserDefinedEnum asset -- authored names, display names, tooltips, numeric values
query-struct	Inspect a UserDefinedStruct asset -- authored member names, defaults, and metadata
inspect-customizable-object-graph	Inspect a Mutable/CustomizableObject graph and return graphs, nodes, pins, edges, and derived node roles
inspect-mutable-parameters	Derive structured Mutable parameter metadata such as groups, defaults, runtime enum options, tags, and related graph links
inspect-mutable-diagnostics	Report Mutable plugin availability and best-effort capability/runtime diagnostics for a target asset
add-co-node	Add a node to a Mutable/CustomizableObject graph by class name, with optional position and properties
add-co-parameter	Add a common Mutable parameter node such as float, color, enum, projector, texture, transform, or mesh
add-co-mesh-option	Add a skeletal or static mesh option node and assign its mesh reference
set-co-base-mesh	Set the mesh reference on an existing CustomizableObject node
add-co-group-child	Connect a child object node into an object group using Mutable's default Object -> Objects pins
set-co-node-property	Set reflected properties or matching pin defaults on a CustomizableObject graph node
connect-co-pins	Connect two CustomizableObject graph pins by node GUID and pin name, with one automatic pin regeneration retry by default
regenerate-co-node-pins	Regenerate pins for one Mutable/CustomizableObject graph node and return the refreshed pin list
compile-co	Compile a CustomizableObject asset and return structured status
remove-co-node	Remove a CustomizableObject graph node by GUID, object path, object name, or title
create-asset	Create new Blueprint, Material, DataTable, World (Level), or other asset types
delete-asset	Delete an asset
release-asset-lock	Best-effort close editors and release UE file handles for a specific asset
set-asset-property	Set a property on a Blueprint CDO or component, including nested InstancedStruct members
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
validate-class-path	Verify that a soft class path exists, loads, and resolves to a UClass

Play-In-Editor (PIE) Control

Command	Description
exec-console-command	Execute arbitrary UE console commands directly in editor, PIE, or game worlds
pie-session	Start, stop, pause, resume PIE -- also query actor state during play
pie-tick	Start PIE if needed and advance the world deterministically by frame count
anim	Canonical animation instance, sync marker, graph authoring, transition, and Rewind command family
inspect-anim-instance	Snapshot a target actor's live UAnimInstance state or inspect static AnimBlueprint topology with --asset-path
inspect-sync-markers	List AuthoredSyncMarkers on an AnimSequence asset
compare-sync-markers	Compare sync marker names and timing across AnimSequence assets
add-sync-marker	Add an AuthoredSyncMarker to an AnimSequence asset
remove-sync-marker	Remove AuthoredSyncMarkers from an AnimSequence asset
inspect-pawn-possession	Inspect controller/pawn links, AI auto-possession, and hidden state in a running world
trigger-input	Send input events to a running game (PIE or packaged build)

Screenshot and Visual Capture

Command	Description
capture	Canonical capture command family for viewport and screenshot capture
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 substring filters, cursors, and follow mode
get-console-var	Read the value of a console variable (CVar)
set-console-var	Set a console variable value

Gameplay Tags

Command	Description
request-gameplay-tag	Resolve a registered GameplayTag by name and return validity/export text
reload-gameplay-tags	Reload GameplayTags settings and refresh tag tables where supported

Python Scripting in UE

Command	Description
run-python-script	Execute a Python script inside UE's embedded Python interpreter, preserving normal file semantics for --script-path and exposing optional PIE-world helpers
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
statetree	Canonical StateTree inspection, state, task, and transition command family
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
umg	Canonical UMG command family for designer apply/inspect, navigation, preview lifecycle, verification, layout, and workflows
inspect-widget-blueprint	Inspect UMG Widget Blueprint hierarchy, bindings, properties, and input mapping key bindings
inspect-runtime-widgets	Inspect live UMG widget geometry during PIE sessions
apply-widget-tree	Build or replace a Widget Blueprint Designer hierarchy from a declarative JSON spec
wire-widget-navigation	Validate named Widget Blueprint buttons, switchers, and target widgets while exposing parent-class navigation binding contracts
verify-umg-workflow	Create or inspect UMG widgets in PIE, validate expected names/text, broadcast button clicks, and assert switcher or visibility outcomes
umg-layout	Unified concept-to-runtime layout pipeline for extraction, geometry/pixel comparison, subset matching, ignore masks, and spec fitting
extract-umg-layout	Normalize designer or runtime UMG geometry into a layout JSON artifact
compare-umg-layout	Compare expected and actual UMG layout artifacts offline
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 from a JSON object keyed by row struct field name

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

Rewind Debugger (Animation Debugging)

Requires the Animation Insights (GameplayInsights) plugin enabled in Edit > Plugins.

Command	Description
anim rewind	Canonical Rewind Debugger recording and inspection command family
rewind-start	Start a Rewind Debugger recording with channel and actor filtering, or load an existing .utrace file with --load
rewind-stop	Stop the current recording
rewind-status	Query current recording state (detects recordings from CLI or editor UI)
rewind-list-tracks	List all recorded actors and their available track types
rewind-overview	Track-level summary for an actor (state machine transitions, montage play ranges, notify fire times)
rewind-snapshot	Detailed animation state at a specific time or frame — the time-travel equivalent of inspect-anim-instance
rewind-save	Save the in-memory recording to a .utrace file

Build and Live Coding

Command	Description
build-and-relaunch	Trigger a full C++ rebuild and optionally relaunch the editor; --wait monitors staged progress, and offline fallback can build from --project when the bridge is unavailable
trigger-live-coding	Trigger a Live Coding compile (hot reload); warns on risky reflected header changes and returns full-build guidance when Unreal cancels unsupported changes
reload-bridge-module	Reload the bridge editor module from disk without a full editor restart

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)
author-umg-designer	Convert a UI concept image plus text requirements into an editable UMG Designer tree JSON draft for apply-widget-tree
author-umg-workflow	Turn a UI concept into an editable UMG Designer tree, stable widget-name navigation contract, and PIE interaction verification plan
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)
replay-changes	Walk the binary-asset conflict recovery flow for Git or Perforce: extract base/local/remote revisions, inspect offline diffs, sync the incoming binary, and replay the wanted local edits manually
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
soft-ue-cli query-level --world pie --search "BP_Player*"
soft-ue-cli get-property BP_Player_C_0 Health --world pie

Call a BlueprintCallable function

soft-ue-cli call-function BP_GameMode SetDifficulty --args '{"Level": 3}'

Compose deterministic runtime steps with one batch

soft-ue-cli batch-call --calls '[
  {"tool":"pie-tick","args":{"frames":1}},
  {"tool":"query-level","args":{"limit":5}},
  {"tool":"get-logs","args":{"lines":5}}
]'

Sweep a pure callable on a transient instance

soft-ue-cli call-function --class-path /Script/Engine.Actor --function-name K2_GetActorLocation --spawn-transient

Validate a class path before spawning

soft-ue-cli validate-class-path /Game/Characters/BP_Hero.BP_Hero_C

Tick PIE and inspect animation state

soft-ue-cli pie-tick --frames 30
soft-ue-cli inspect-anim-instance --actor-tag TestCharacter --include state_machines,montages

Execute a console command directly in PIE

soft-ue-cli exec-console-command stat fps
soft-ue-cli exec-console-command --player-index 0 MyGame.MyCommand arg1 arg2

Inspect possession state during PIE

soft-ue-cli inspect-pawn-possession
soft-ue-cli inspect-pawn-possession --class-filter Character

Inspect a Blueprint's components and variables

soft-ue-cli query-blueprint /Game/Blueprints/BP_Player --include components,variables

Build an editable UMG Designer tree

soft-ue-cli apply-widget-tree /Game/UI/WBP_MainMenu --spec-file menu_tree.json --compile --save
soft-ue-cli wire-widget-navigation /Game/UI/WBP_MainMenu --bindings-file navigation.json --compile --save
soft-ue-cli verify-umg-workflow --widget-class /Game/UI/WBP_MainMenu.WBP_MainMenu_C --expected-widgets-file expected_widgets.json --click-sequence-file clicks.json --capture-after
soft-ue-cli umg-layout extract --source concept-image --input concept.png --output concept_layout.json
soft-ue-cli umg-layout extract --source designer --asset-path /Game/UI/WBP_MainMenu --output umg_expected_layout.json
soft-ue-cli umg-layout extract --source runtime --root-widget WBP_MainMenu_C_0 --full-geometry --output umg_runtime_layout.json
soft-ue-cli umg-layout compare --mode geometry --subset concept_layout.json umg_runtime_layout.json --output umg_layout_report.json
soft-ue-cli umg-layout fit --concept concept_layout.json --actual umg_runtime_layout.json --spec menu_tree.json --output corrected_menu_tree.json
soft-ue-cli inspect-widget-blueprint /Game/UI/WBP_MainMenu --include-defaults --depth-limit 8
soft-ue-cli skills get author-umg-workflow

wire-widget-navigation fails fast while PIE is active or the editor is saving/garbage collecting because it mutates WidgetBlueprint assets. Stop PIE first, wait until the editor is idle, or pass --allow-pie / --allow-busy when you intentionally accept that risk.

Inspect and diff local .uasset files offline

soft-ue-cli inspect-uasset D:/Project/Content/Blueprints/BP_Player.uasset --sections all
soft-ue-cli inspect-uasset D:/Project/Content/Characters/SK_Mannequin_Skeleton.uasset --sections properties
soft-ue-cli inspect-uasset D:/Project/Content/__ExternalActors__/Maps/OpenWorld/5/TQ/ABC123.uasset --sections summary,properties
soft-ue-cli diff-uasset D:/snapshots/BP_Player_before.uasset D:/Project/Content/Blueprints/BP_Player.uasset --sections variables,functions
soft-ue-cli diff-uasset D:/snapshots/SK_before.uasset D:/Project/Content/Characters/SK_Mannequin_Skeleton.uasset --sections properties
soft-ue-cli diff-uasset D:/snapshots/Actor_before.uasset D:/Project/Content/__ExternalActors__/Maps/OpenWorld/5/TQ/ABC123.uasset --sections summary,properties

Inspect UserDefinedEnum and UserDefinedStruct assets

soft-ue-cli query-enum /Game/Data/E_TraversalActionType
soft-ue-cli query-struct /Game/Data/S_TraversalCheckResult

Inspect Mutable / CustomizableObject assets safely

soft-ue-cli inspect-customizable-object-graph /Game/Characters/CO_Hero.CO_Hero
soft-ue-cli inspect-mutable-parameters /Game/Characters/CO_Hero.CO_Hero
soft-ue-cli inspect-mutable-diagnostics /Game/Characters/CO_Hero.CO_Hero

Edit Mutable / CustomizableObject assets

soft-ue-cli add-co-parameter /Game/Characters/CO_Hero.CO_Hero BodyHeight --parameter-type float
soft-ue-cli add-co-mesh-option /Game/Characters/CO_Hero.CO_Hero /Game/Meshes/SKM_Boots.SKM_Boots
soft-ue-cli add-co-group-child /Game/Characters/CO_Hero.CO_Hero <group-node-guid> <child-node-guid>
soft-ue-cli regenerate-co-node-pins /Game/Characters/CO_Hero.CO_Hero <node-guid>
soft-ue-cli connect-co-pins /Game/Characters/CO_Hero.CO_Hero <source-node-guid> Value <target-node-guid> Input
soft-ue-cli compile-co /Game/Characters/CO_Hero.CO_Hero
soft-ue-cli remove-co-node /Game/Characters/CO_Hero.CO_Hero <node-guid>

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 trigger-input action --action-name IA_SwitchCharacter
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

Create an AnimBlueprint state machine

soft-ue-cli add-anim-state-machine /Game/ABP_Hero Locomotion --default-state Idle
soft-ue-cli add-anim-state /Game/ABP_Hero Locomotion Run --position 500,0
soft-ue-cli add-anim-transition /Game/ABP_Hero Locomotion Idle Run --rule true
soft-ue-cli add-graph-node /Game/ABP_Hero AnimGraphNode_SequencePlayer --graph-name Run

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

Refresh GameplayTags after editing config

soft-ue-cli reload-gameplay-tags
soft-ue-cli request-gameplay-tag Status.Effect.Burning

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 list

# Feed 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-enum /Game/Data/E_Dependency
#   soft-ue-cli query-struct /Game/Data/S_Dependency
#   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
#   soft-ue-cli capture-viewport --source editor --scale 50 --color-mode grayscale
# 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:

1. --server command-line flag
2. SOFT_UE_BRIDGE_URL environment variable
3. SOFT_UE_BRIDGE_PORT environment variable (constructs http://127.0.0.1:<port>)
4. .soft-ue-bridge/instance.json file (searched upward from the current working directory -- written automatically by the plugin at startup)
5. 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, DebugGame, Development; Shipping only if explicitly opted in
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"

Do not include project-specific information, personal information, or any clue that could identify your project. Replace project names, internal paths, asset names, emails, tokens, and other sensitive details with generic placeholders.

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"

Do not include project-specific information, personal information, or any clue that could identify your project. Replace project names, internal paths, asset names, emails, tokens, and other sensitive details with generic placeholders.

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, in Development and DebugGame packaged builds by default. The bridge module now uses Unreal's DeveloperTool module type, so Shipping builds exclude it unless the target explicitly enables developer tools (for example via bBuildDeveloperTools = true).

The plugin descriptor restricts SoftUEBridge's editor-only dependency plugins to Editor targets, so Python/editor scripting dependencies are not enabled for packaged game targets.

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. Shipping builds exclude the bridge by default; if you intentionally need it there, enable developer tools for that target.

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