CET

MCP server that connects Claude Code to Cyber Engine Tweaks (CET) in Cyberpunk 2077. Execute Lua code, query game state, manipulate TweakDB, manage inventory, and observe game events — all from your terminal while the game is running.

How it works

Claude Code → stdio/JSON-RPC → MCP Server → TCP (RedSocket) → CET Bridge Mod → Game Engine

The MCP server runs as a Claude Code subprocess. It opens a TCP server on localhost:27010. The CET Bridge Mod (Lua) connects to it via RedSocket and executes commands in the game's Lua VM. Falls back to file-based IPC automatically if RedSocket is not installed or if the TCP port is already in use (multiple sessions supported).

Pairs with WolvenKit MCP for a complete AI-assisted modding pipeline.

Requirements

• Node.js >= 18
• Cyberpunk 2077 with Cyber Engine Tweaks >= 1.32
• RED4ext >= 1.25
• RedSocket (recommended — enables TCP transport, ~1ms latency vs ~16-33ms with file IPC)

Setup

# 1. Clone and build
git clone https://github.com/y4rd13/cyber-engine-tweak-mcp.git
cd cyber-engine-tweak-mcp
npm install
npm run build

# 2. Copy CET mod to game directory
cp -r cet-mod/CETBridge "/path/to/Cyberpunk 2077/bin/x64/plugins/cyber_engine_tweaks/mods/CETBridge"

# 3. Add to Claude Code globally
claude mcp add cet-bridge -s user \
  -e "CET_BRIDGE_DIR=/path/to/cyber_engine_tweaks/mods/CETBridge" \
  -e "CET_TRANSPORT=tcp" \
  -- node /path/to/cyber-engine-tweak-mcp/build/index.js

Tools (37)

Execution

Tool	Description
execute_lua	Run Lua code in the CET console
evaluate_expression	Evaluate a Lua expression and return the result
batch_execute	Execute multiple Lua statements in one round-trip

Game State

Tool	Description
get_player_info	Player level, health, street cred, position
get_game_state	In-game time, scene tier, weather, zone type
add_item	Add item to inventory by TweakDB ID
teleport	Teleport player to world coordinates
set_time	Change in-game time of day
set_weather	Change weather (Sunny, Rain, Fog, Sandstorm, etc.)

Inventory

Tool	Description
get_inventory	List player inventory with type filtering
remove_item	Remove items from inventory
get_equipped	Show currently equipped weapons, clothing, cyberware

Player

Tool	Description
set_stat	Modify player stats (Health, Armor, Level, etc.)
apply_status_effect	Apply buffs/debuffs to the player
remove_status_effect	Remove status effects
get_active_effects	List all active status effects on the player
toggle_god_mode	Toggle invulnerability on/off
set_level	Set player level and/or street cred directly
get_appearance_info	Get player's current visual appearance
get_vehicle_list	List all vehicles in the player's garage

World

Tool	Description
spawn_vehicle	Spawn a vehicle near the player
get_nearby_entities	Scan for nearby NPCs, vehicles, items
kill_nearby_npcs	Kill hostile (or all) NPCs in radius
show_notification	Show in-game UI notification
play_sound	Play a sound event in-game
get_scanner_info	Get info about the entity you're looking at

Quest

Tool	Description
get_quest_fact	Read a quest progression flag
set_quest_fact	Set a quest progression flag

TweakDB

Tool	Description
get_tweakdb_value	Read a TweakDB flat or record
set_tweakdb_value	Write a TweakDB flat value
search_tweakdb	Search TweakDB records by pattern
dump_type	Introspect a game RTTI type (methods, properties)

Observation

Tool	Description
observe_events	Subscribe to game events via CET Observe
get_observations	Read buffered event observations

Dev Tools

Tool	Description
get_connection_status	Check bridge connectivity and transport type
read_log	Read CET scripting.log
list_mods	List installed CET mods

Configuration

Variable	Default	Description
CET_BRIDGE_DIR	(see .mcp.json)	Path to CETBridge mod directory
CET_TRANSPORT	tcp	Transport: tcp (RedSocket) or file (fallback)
CET_TCP_PORT	27010	TCP server port

Multi-Session Support

Multiple Claude Code sessions can use cet-bridge simultaneously:

• First session: binds TCP port 27010 (fast, ~1ms)
• Additional sessions: automatically fall back to file-based IPC (~16-33ms)
• No session crashes — the fallback is seamless

Architecture

See docs/architecture.md for detailed diagrams.

Component	Language	Role
MCP Server	TypeScript	stdio transport for Claude Code, TCP server for game bridge
CET Bridge Mod	Lua	Runs in-game, dispatches commands to CET Lua VM

Development

npm run build    # Compile TypeScript
npm run dev      # Watch mode
npm run inspect  # Test with MCP Inspector

After changing Lua files, copy them to the game directory:

cp cet-mod/CETBridge/*.lua "/path/to/cyber_engine_tweaks/mods/CETBridge/"

Safety

• TCP binds to localhost only — no network exposure
• All user code runs in pcall() — errors are caught, never crash the game
• This is a development tool — not intended for multiplayer or production use
• Infinite loops in executed Lua will freeze the game (no mitigation possible without native code)

License

MIT