MCP tool reference

Every tool replies in plain text written for a model to read (stats replies in JSON). Tools that act take a player id, default 1. Tools that take time step the world until the action is done, then report what happened in the meantime: hits, strikes on players, thumps on doors, anything broken, deaths and their cause, skill level-ups.

Positions are in metres; one tile is one metre. Facing is in radians, or a compass direction where a tool takes one. There are 20 ticks to a second.

What the server tells your app

Besides its name, description and arguments, every tool has a title (a short name for people) and annotations:

• Read-only tools (readOnlyHint: true): everything under Looking, the tables (weapons, items, loot, recipes), inventory, containers_near, health, skills and saves. They take no game time and change nothing, so apps that ask before each call can let these through without asking.
• Debug tools: their titles start with Debug:, their descriptions with “Debug tool, for setting up tests”, and they carry _meta: {"zombye/debug": true}. They are the tools under Debug, and load.
• Only save (it replaces a save of the same name) and load (it replaces the world) are marked destructive. No tool reaches outside the game (openWorldHint: false).

stats has an outputSchema, and returns its JSON as structuredContent as well as text.

The server also sends a few lines of instructions when an app connects, which most apps pass on to the model: you are player 1, time only moves when a tool steps it, look with observe first, and the debug tools are for testing.

Start the server with --no-debug-tools to leave the debug tools out: they aren’t listed and can’t be called. That makes an agent play by the rules, and brings the list down from 47 tools to 37 for apps that cap how many they take.

The server speaks MCP’s stateless revision (2026-07-28: no initialize, server/discover describes the server, each request names its version) and the older handshake revisions (2024-11-05 to 2025-11-25) side by side, so both new and old apps connect.

Looking

Tool	Arguments	What it does
observe	radius, x, y	A text map around player 1 (or a point), then the players, items on the floor, damaged doors and windows, and the nearest zombies with their state.
screenshot	player, x, y, zoom, angle, width, height	A rendered PNG as the game draws it, with the player’s fog of war and the walls between the camera and the player cut away. No HUD. 960 × 540 unless you give width and height (up to 1920 × 1080). About a second; changes nothing.
stats		JSON (as text and as structured content): time, players (health, needs, wounds, skills, this run’s numbers, cause of death), zombies by state and tier, population, tick timings, the state hash.
zombie	id	One zombie’s tier, health, state, target, memory and timers, and what it can see of each player.
edge	x, y	The four edges of a tile: wall, window, door, arch or fence, and hit points for doors and windows.
buildings		Every building: template, bounds, storeys, ground-floor rooms. Marks the one you wake up in.
regions		Zombie population, targets and noise attractors per 64 m region, as text heat maps.

The map legend

Symbol	Meaning
- |	Walls
= !	Shut windows
o x	Open and broken windows (on a wall line)
D d	Shut door, damaged shut door
/ #	Open door, broken door
~	Fence
. , : _	Grass, road, sidewalk or path, indoor floor
T *	Tree, bush
f c o	Furniture, an unsearched container, a searched container (on a tile)
w i	A weapon, any other item on the floor
P X	A player, a dead player
@ G	Where the player woke up, the debug goal
Z I C L A B	Zombies wandering, investigating, chasing, lunging, attacking, battering
S v %	Staggered, down, a corpse
n ?	Zombies on the cheaper near and far simulation tiers

Moving and the world

Tool	Arguments	What it does
step_ticks	n	Let time pass.
move_player	player, direction or dx/dy, ticks, run, sneak, facing	Hold a movement input for some ticks, then stop. Walk 3 m/s, run 5.5, sneak 1.4.
interact	player	Open or shut the door or window the player faces, within 1.6 m.
smash_window	player	Smash the window the player faces. Loud.
sleep	player, max_hours	Lie down (bed, sofa or floor) and sleep until something wakes the player. Says why it woke.
respawn	player	A dead player gets up in the bedroom, with full health and empty hands.
say	player, text, volume	Says a line to whoever is near: whisper (3 m), talk (12 m, the default) or shout (40 m); 0.4 of that through a wall. Zombies hear it too (1.5, 7 and 30 m). Time doesn’t move.
heard	player, secs	Read-only. What the player heard said lately: how long ago, how loud, muffled or not, from where, and from whom when known (with PvP on, only if it saw the speaker).
gesture	player, gesture	wave, hands_up (held until lowered), point, or none. Others see it; observe and stats show it.

Fighting

Tool	Arguments	What it does
attack	player, facing or target	Swing what’s in hand (or punch). Turns to target (a zombie id) first if given.
shove	player, facing or target	Push back up to three zombies in front. No damage; always staggers.
stomp	player, facing or target	Stamp on a downed zombie at the player’s feet.
weapons		The weapon table as the game read it.

Things

Tool	Arguments	What it does
inventory	player	Hands, back, shoulder, worn, carried (with indices), load, the open container, the floor in reach, containers in reach, queued jobs.
containers_near	player, radius	Containers nearby: id, kind, room, distance, searched or not, and what’s in them or the table they’ll fill from.
search	player, container	Open a container in reach (by id, or the one faced). Lists what’s inside.
take	player, from, index, count	Take from the open container (from: "container") or the floor (from: "ground", index = ground item id).
pick_up	player	The instant grab: the item on the floor in front. A weapon goes into the hand.
move_item	player, from, index, to, count	Move a stack between carried, hand, off_hand, back, shoulder, worn, container, ground.
equip	player, index	Put a carried stack where it belongs: a bag on, a weapon in hand.
wear	player, index	Put on carried clothing.
unequip	player, from, index	Take off or let go into the bags (or the floor).
drop	player, from, index, count	Drop at the player’s feet.
use	player, from, index	Eat or drink one go. Says beforehand what it will do, then the needs before and after.
items	category	The item table.
loot	room, container, n	A loot table, and n sample fills of it.

Health and crafting

Tool	Arguments	What it does
health	player	Health, every wound (with its # id), what each needs, pain, illness, needs and status tags.
treat	player, action, wound or part, item	First aid: dress, clean, stitch, remove, painkillers, antibiotics. Picks the most urgent wound and the best item if not told.
skills	player	Each skill’s level, XP, what it gives now and next, and how it’s earned.
recipes		Every recipe.
craft	player, recipe	Without a recipe: what the player can make and what’s missing for the rest. With one: makes it.

Saves

Tool	Arguments	What it does
save	name	Save the world to a named save in the saves folder, or with no name to the --save file.
load	name, force	Replace the world with a save. force loads one whose game data changed in a way it can’t simply take.
saves		The saves folder, and where this session autosaves.

Debug

For testing and modding, not for fair play. --no-debug-tools leaves them out.

Tool	Arguments	What it does
dev	player, god, ignored	God mode, and zombies ignoring the player.
spawn_item	item, count, x, y	Put items on the floor.
spawn_zombies	count, x, y, radius	Put zombies on open tiles in a circle.
make_noise	x, y, radius, lasting	A noise. A loud one (25 m or more) also draws far zombies in over minutes.
set_goal	x, y	Every zombie within 120 m heads for a point, senses off. No arguments goes back to normal.
skip_time	hours	Move the clock on.
set_needs	player, hunger, thirst, tiredness	Set needs, 0 fine to 1 worst.
wound	player, part, kind, infected	Give the player a wound.
add_player	x, y	Another player joins.
load	name, force	See Saves: it swaps the whole world, so it goes with the debug tools.

For scale when making noise: walking is 6 m, running 14, a door 10, a zombie groaning 9, a zombie thumping a door 15, breaking glass 22, breaking a door 26.