Let AI agents play Mount & Blade II: Bannerlord.
Bannerlord.GABS is a mod that exposes 90+ game tools via the GABS ecosystem, enabling AI agents (Claude, GPT, etc.) to observe game state, navigate menus, trade, recruit, negotiate, craft weapons, manage diplomacy, and more — all through tool calls over MCP.
AI Agent ←— MCP —→ GABS (Go binary) ←— GABP (TCP) —→ Bannerlord.GABS (this mod) ←— Game API —→ Bannerlord
| Category | Examples |
|---|---|
| Campaign Map | Travel between settlements, recruit troops, buy/sell goods, manage inventory |
| Conversations | Talk to NPCs, navigate dialogue trees, handle persuasion checks |
| Diplomacy | Become a mercenary, declare war, make peace, change relations |
| Trading | Check market prices, buy low / sell high, manage caravans |
| Smithing | Refine materials, smelt weapons, forge custom weapons — all via UI tools |
| UI Interaction | Click buttons, read ViewModels, navigate any Gauntlet UI screen |
| Combat | Auto-resolve battles (Send Troops), manage formations, retreat |
| Threat Detection | Scan for hostiles, direction-aware flee to safety |
| Game Management | Start new games, load/save, skip videos, advance time |
- GABS (v0.2.0+) — the MCP server
- BLSE — Bannerlord Software Extender (recommended launcher)
- Bannerlord.Harmony, ButterLib, MCM — required BUTR modules
Download from NexusMods or GitHub Releases and extract to:
<Game>/Modules/Bannerlord.GABS/
gabs games add bannerlordSet the launch command to use the PowerShell script (handles Safe Mode bypass):
{
"command": "powershell.exe",
"args": [
"-ExecutionPolicy",
"Bypass",
"-File",
"path/to/launch-bannerlord.ps1"
],
"workingDirectory": "<Game>/bin/Win64_Shipping_Client",
"stopProcessName": "Bannerlord.BLSE.Standalone.exe"
}Add GABS as an MCP server in your AI tool's configuration:
Claude Code (~/.claude/settings.json):
{
"mcpServers": {
"gabs": {
"command": "gabs",
"args": ["server"]
}
}
}games.start { gameId: "bannerlord" }
games.connect { gameId: "bannerlord" }
bannerlord.core.load_save { saveName: "your_save" }
bannerlord.core.wait_for_state { expectedState: "campaign_map" }
See docs/setup-guide.md for detailed setup instructions.
| Category | Tools | Description |
|---|---|---|
core/* |
ping, get_game_state, load_save, save_game, set_time_speed, check_blockers, new_game, ... | Game lifecycle and state |
hero/* |
get_player, get_hero, list_heroes, get_skills, get_traits, get_relationships, kill_hero | Hero information and actions |
party/* |
get_player_party, move_to_settlement, recruit_all, detect_threats, flee_to_safety, wait_for_arrival, ... | Party movement and management |
settlement/* |
list_settlements, get_settlement, get_market_prices, get_workshops | Settlement queries |
kingdom/* |
list_kingdoms, get_kingdom, get_clan, list_wars | Kingdom and diplomacy info |
inventory/* |
get_inventory, buy_item, sell_item, add_gold, give_gold | Economy and items |
diplomacy/* |
declare_war, make_peace, change_relation | Diplomatic actions |
conversation/* |
start, get_state, select_option, continue, get_persuasion, wait_for_state | NPC dialogue |
menu/* |
get_current, select_option | Game menu interaction |
barter/* |
get_state, offer_item, accept, cancel | Trading with NPCs |
ui/* |
get_screen, click_widget, get_viewmodel_property, call_viewmodel_method, answer_inquiry, ... | Universal UI interaction |
battle/* |
get_state, get_formations, order_charge, order_hold, order_retreat, ... | Battle commands |
quest/* |
list_quests, get_quest | Quest tracking |
history/* |
get_recent_events, get_events_by_type | Campaign event history |
Action tools return immediately. Use companion awaiter tools to block until completion — never use sleep.
party/move_to_settlement → party/wait_for_arrival → next action
core/load_save → core/wait_for_state → next action
conversation/start → conversation/wait_for_state → read dialogue
Most game screens are accessible through ui/get_screen, ui/click_widget, and ui/get_viewmodel_property. The ViewModel property reader supports:
- Dot-notation:
Smelting.SmeltableItemList - Array indexing:
WeaponDesign.PieceLists[0].Pieces - Deep paths:
WeaponDesign.PieceLists[0].SelectedPiece.TierText
- Setup Guide — Install GABS, configure Bannerlord, add MCP, deploy the mod
- Getting Started — Quick start, workflows, safe travel protocol
- Starting a New Game — Character creation, culture selection
- Early Game Strategy — Wealth, recruiting, mercenary service, flee tactics
- Mid Game Strategy — Vassalage, workshops, army composition
- Late Game Strategy — Kingdom creation, conquest, endgame
- Smithing — Refine, smelt, forge with full UI tool workflows
- Courtship & Marriage — 8-step marriage walkthrough
- Mercenary Contract — Becoming a mercenary
- Console Commands — 88 campaign console commands
- Campaign Actions — 61 action classes
- Gauntlet UI — Screen/layer/widget architecture
- Barter System — Barter API reference
Bannerlord.GABS/
├── AGENTS.md # Agent instructions (read by AI tools)
├── README.md # This file
├── launch-bannerlord.ps1 # Game launcher with Safe Mode bypass
├── docs/
│ ├── setup-guide.md
│ ├── gameplay/ # Strategy and workflow guides
│ └── *.md # API reference docs
└── src/
├── Bannerlord.GABS.sln
└── Bannerlord.GABS/
├── SubModule.cs # Mod entry point, GABP server setup
├── MainThreadDispatcher.cs # Thread-safe game API access
└── Tools/
├── CoreTools.cs # Game state, saves, time, commands
├── HeroTools.cs # Hero queries and actions
├── PartyTools.cs # Party movement, combat, flee
├── SettlementTools.cs # Settlement and market queries
├── KingdomTools.cs # Kingdom and diplomacy
├── InventoryTools.cs # Economy and items
├── ConversationTools.cs # NPC dialogue system
├── MenuTools.cs # Game menu interaction
├── BarterTools.cs # Barter/trade with NPCs
├── BattleTools.cs # Battle commands
├── GauntletUITools.cs # Universal UI interaction
├── QuestTools.cs # Quest tracking
├── HistoryTools.cs # Campaign event history
└── DiplomacyTools.cs # War, peace, relations
Requires:
- .NET SDK 8.0+
BANNERLORD_BETA_DIRorBANNERLORD_GAME_DIRenvironment variable pointing to your game installsupported-game-versions.txtin the project root (e.g.v1.3.15)
dotnet build src/Bannerlord.GABS/Bannerlord.GABS.csproj -c Beta_DebugThe SDK auto-deploys the built mod to <Game>/Modules/Bannerlord.GABS/.
