UE Audio MCP Plugin — TCP Control

Drive the C++ TCP server inside Unreal Editor. All commands use 4-byte big-endian length prefix + UTF-8 JSON on 127.0.0.1:9877.

Connection

# Python SDK
from ue_audio_mcp.ue5_connection import get_ue5_connection
conn = get_ue5_connection()
resp = conn.send_command({"action": "ping"})

# Raw TCP
python3 -c "
import socket, struct, json
s = socket.socket(); s.settimeout(5); s.connect(('127.0.0.1', 9877))
p = json.dumps({'action':'ping'}).encode()
s.sendall(struct.pack('>I', len(p)) + p)
r = s.recv(4); l = struct.unpack('>I', r)[0]; print(json.loads(s.recv(l)))
"

All 24 Commands

System

Builder Lifecycle

Graph I/O

Nodes

__graph__ = sentinel node ID for graph boundary connections.

Audition

Variables (UE 5.7+)

Presets

Query

Blueprint & Assets

Allowlisted functions: PlaySound2D, PlaySoundAtLocation, SpawnSoundAtLocation, SpawnSound2D, SetSoundMixClassOverride, ClearSoundMixClassOverride, PushSoundMixModifier, PopSoundMixModifier, SetGlobalPitchModulation, SetGlobalListenerFocusParameters, PlayDialogue2D, PlayDialogueAtLocation, SpawnDialogue2D, SpawnDialogueAtLocation, GetPlayerCameraManager, GetPlayerController, GetPlayerPawn.

class_filter values: Blueprint, WidgetBlueprint, AnimBlueprint, MetaSoundSource, MetaSoundPatch, SoundWave, SoundCue, SoundAttenuation, SoundClass, SoundConcurrency, SoundMix, ReverbEffect.

Key Pin Names

• Sine/Saw/Square/Triangle: IN: Frequency, Phase Offset, Glide, Bias; OUT: Audio
• AD Envelope: IN: Trigger, Attack Time, Decay Time; OUT: Out Envelope
• ADSR Envelope: IN: Trigger Attack, Trigger Release, Attack Time, Decay Time, Sustain Level, Release Time; OUT: Out Envelope
• Biquad Filter: IN: In, Cutoff Frequency, Bandwidth, Filter Type; OUT: Out
• Wave Player: IN: Play, Stop, Wave Asset, Start Time, Loop, Pitch Shift; OUT: Out Audio, On Finished
• Multiply/Add (Audio): IN: Primary Operand, Operand; OUT: Out
• Map Range: IN: Value, In Range A, In Range B, Out Range A, Out Range B, Clamped; OUT: Out

Full pin reference: scripts/ms_node_specs.json (93 nodes, 464 pins)

Example Workflows

Simple Sine → Output

{"action":"create_builder", "asset_type":"Source", "name":"MySine"}
{"action":"add_interface", "interface":"MetaSound"}
{"action":"add_graph_output", "name":"Out Mono", "type":"Audio"}
{"action":"add_node", "id":"osc", "node_type":"UE::Sine::Audio"}
{"action":"set_default", "node_id":"osc", "input":"Frequency", "value":440}
{"action":"connect", "from_node":"osc", "from_pin":"Audio", "to_node":"__graph__", "to_pin":"Out Mono"}
{"action":"build_to_asset", "name":"MySine", "path":"/Game/Audio/MCP"}

Filtered Synth with Envelope

{"action":"create_builder", "asset_type":"Source", "name":"FilteredSynth"}
{"action":"add_interface", "interface":"MetaSound"}
{"action":"add_graph_output", "name":"Out Mono", "type":"Audio"}
{"action":"add_graph_input", "name":"Cutoff", "type":"Float", "default":"2000.0"}
{"action":"add_node", "id":"osc", "node_type":"UE::Saw::Audio"}
{"action":"add_node", "id":"filt", "node_type":"UE::Biquad Filter::Audio"}
{"action":"add_node", "id":"env", "node_type":"AD Envelope"}
{"action":"add_node", "id":"mul", "node_type":"UE::Multiply::Audio"}
{"action":"connect", "from_node":"osc", "from_pin":"Audio", "to_node":"filt", "to_pin":"In"}
{"action":"connect", "from_node":"__graph__", "from_pin":"Cutoff", "to_node":"filt", "to_pin":"Cutoff Frequency"}
{"action":"connect", "from_node":"filt", "from_pin":"Out", "to_node":"mul", "to_pin":"Primary Operand"}
{"action":"connect", "from_node":"env", "from_pin":"Out Envelope", "to_node":"mul", "to_pin":"Operand"}
{"action":"connect", "from_node":"mul", "from_pin":"Out", "to_node":"__graph__", "to_pin":"Out Mono"}
{"action":"build_to_asset", "name":"FilteredSynth", "path":"/Game/Audio/MCP"}

Project Scan

{"action":"list_assets", "class_filter":"Blueprint"}
{"action":"scan_blueprint", "asset_path":"/Game/BP_Player", "audio_only":true}
{"action":"list_assets", "class_filter":"MetaSoundSource"}
{"action":"get_node_locations", "asset_path":"/Game/Audio/MS_Gunshot"}

Or batch: python scripts/scan_project.py --full-export --import-db --rebuild-embeddings

Gotchas

• Must call create_builder before any node/connection ops
• __graph__ is NOT a real node — it’s the boundary sentinel
• Path must start with /Game/ or /Engine/, no ..
• Audio vs Float: cannot cross-connect — use correct node variant
• TCP drops after ~17 rapid commands — use reconnect with progressive delay
• Builder state is global — only one active builder at a time
• list_node_classes discovers real class names — the 65-name registry may miss some

Source Files

• C++ commands: ue5_plugin/UEAudioMCP/Source/UEAudioMCP/Private/Commands/
• TCP server: ue5_plugin/UEAudioMCP/Source/UEAudioMCP/Private/AudioMCPTCPServer.cpp
• Python tools: src/ue_audio_mcp/tools/
• Node registry: src/ue_audio_mcp/knowledge/metasound_nodes.py (144 nodes, 798 pins)

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