name: create-mob description: Create a new mob (custom entity) for a Minecraft Bedrock Edition add-on from a plain description, or change an existing one, including its health, attacks, AI behavior, taming, riding, drops, and natural spawning. Use this whenever someone wants a new creature, monster, animal, pet, boss, or NPC, or wants to change how one of their mobs behaves, for example "make a rideable red panda", "add a goblin that spawns in swamps at night", "make my goblin scared of zombies", or "give the goblin more health". For items use create-item, for blocks use create-block, and for changing how a mob looks use design-model. Not for Minecraft Java Edition mods. metadata: version: "1.0.1"

Create or change a mob

A working mob spans several files across two packs: the behavior pack entity, a client entity, geometry, texture, render controller, and optionally a loot table and spawn rule. For a new mob, the Minecraft Creator Tools MCP tool createMinecraftContent writes all of them in one call; your job is to translate the request into its definition, then check and finish what it produces. For a mob that already exists, skip to "Changing an existing mob".

1. Understand the request

Work out, or choose sensible defaults for:

• Name and a short lowercase ID (swamp_goblin).
• Attitude: hostile, neutral, or passive. How it fights, if at all.
• Size and rough look (body type, colors).
• Special behaviors: tameable, rideable, breedable, flies, swims, avoids or hunts certain mobs.
• Drops, and where and when it spawns (or summon-only).

Only ask the user when an answer would change the design a lot. Otherwise pick defaults and say what you chose at the end.

2. Pick the project folder and namespace

• Existing project (has behavior_packs/): reuse its namespace. Look at the identifier values in existing files (goblins:...).
• New project: use an empty folder and a short lowercase namespace made of letters, digits, and underscores, such as the creator's name or the add-on's theme. Never use minecraft.

3. Generate with createMinecraftContent

Pass outputPath as the project folder itself; don't add a subfolder. The tool's input schema lists every field, and references/behaviors.md maps common requests to traits, behavior presets, and native components.

A typical entity entry:

{
  "id": "swamp_goblin",
  "displayName": "Swamp Goblin",
  "traits": ["humanoid", "hostile", "melee_attacker"],
  "behaviors": ["wander", "hide_from_sun", "look_at_player"],
  "health": 16,
  "attackDamage": 3,
  "scale": 0.5,
  "families": ["goblin", "monster"],
  "appearance": {
    "primaryColor": "#4F7A3A",
    "secondaryColor": "#6B4E2E",
    "textureStyle": "organic",
    "eyes": "glowing"
  },
  "drops": [{ "item": "minecraft:brown_mushroom", "count": { "min": 1, "max": 2 } }],
  "spawning": { "biomes": ["swamp"], "lightLevel": { "max": 7 }, "weight": 20, "groupSize": { "min": 1, "max": 3 } }
}

Use components for anything traits don't cover; they're native Minecraft components and override trait defaults.

4. Check what was generated

The generator doesn't report everything it skipped, so open the files and compare them with the request. Known gaps as of Creator Tools 0.17:

• Unknown fields are silently dropped. If a value you passed isn't in the output, check the field name against the tool's input schema.
• The summary can say "0 loot tables / 0 spawn rules" even when inline drops and spawning created them. Trust the files, not the summary.
• `drops[].chance` isn't applied. Add a condition to the entry in loot_tables/entities/<id>.json: "conditions": [{ "condition": "random_chance", "chance": 0.3 }]. For player-kill-only drops add { "condition": "killed_by_player" }.
• `spawning.timeOfDay` isn't applied. For night or dark-only spawning use "lightLevel": { "max": 7 }, which produces a minecraft:brightness_filter.
• `population_control` is always `animal`. Change it to monster in spawn_rules/<id>.json for hostile mobs, or water_animal for aquatic ones, so they share the right mob cap.
• Adding to an existing project rewrites both manifests. The behavior pack's dependency on its resource pack gets a new UUID that points at nothing, and header.name is reset. Check git diff (or compare with a copy you made first) and restore the original manifest values. The debug-addon validation script reports a broken dependency as [PACKDEP].
• `tameable`, `rideable`, and `breedable` configuration objects are ignored. The traits always use bones to tame, wheat to breed, and a saddle to ride. Edit the generated minecraft:tameable, minecraft:breedable, and minecraft:rideable components as described in references/behaviors.md.
• Trait component groups can override your components. For example, the hostile trait adds a hostile_angry group with its own minecraft:behavior.nearest_attackable_target (targeting players) when the mob spawns, replacing a targeting component you put in components. Merge your targets into the group's entity_types list instead of defining the component twice.

5. Give it a readable name

Creator Tools doesn't create localization, so in game the mob shows as entity.<namespace>:<id>.name. Run the debug-addon skill's names script, passing the display name the user asked for. <debug-addon-skill-folder> is the debug-addon skill's folder, next to this skill's folder; if it's missing, install the debug-addon skill too.

node "<debug-addon-skill-folder>/scripts/add-missing-names.mjs" <project-folder> --name "swampy:swamp_goblin=Swamp Goblin"

It writes entity.swampy:swamp_goblin.name and the spawn egg name to resource_packs/<pack>/texts/en_US.lang, creating the file if needed.

6. Make it look right

The default geometry is a generic body for the chosen type, with a generated texture. If the user described a specific look, use the design-model skill with modelId set to the mob's ID. Afterwards, make sure geometry.default in resource_packs/<pack>/entity/<id>.entity.json matches the new .geo.json identifier; otherwise the mob is invisible.

7. Validate

Follow the debug-addon skill: run its validation script, add pack icons (new projects don't have them), and fix errors until none remain.

8. Tell the user

Summarize the files created, the defaults you picked, and anything you couldn't do. Explain how to try it: enable both packs on a world with cheats on, then use /summon <namespace>:<id> or the spawn egg from the creative inventory. To look at it without Minecraft, they can run npx -y @minecraft/creator-tools@latest view -i <project-folder>.

Changing an existing mob

Most requests in an existing project are changes: "more health", "make it scared of zombies", "tame it with fish instead". If the mob is a vanilla one (such as minecraft:wolf) that isn't in the project, say that changing vanilla mobs isn't covered by these skills yet, and offer to make a custom mob based on it instead.

1. Find the mob's behavior pack file (behavior_packs/<pack>/entities/*.json, matched by identifier). For a quick overview of what it already does, getEffectiveContentSchema on the project folder summarizes each mob as traits and properties.
2. Edit the JSON directly. Running createMinecraftContent again won't help: it leaves files that already exist untouched, so new values never reach the mob.
3. Look at components, then component_groups and events. A component in an active group replaces the one of the same name in components, so change it where it's actually in effect. references/behaviors.md has native components for common requests (targeting, fleeing, protecting the owner).
4. Keep priority values sensible: lower numbers win, so a "flee" behavior must have a lower number than "wander" to interrupt it.
5. Validate with the debug-addon skill, and tell the user what changed and how to see it in game.

If the MCP tools aren't available

This skill needs the Minecraft Creator Tools MCP server (npx -y @minecraft/creator-tools@latest mcp). If its tools are missing, tell the user and suggest adding that server. As a fallback, npx -y @minecraft/creator-tools@latest add --help lists template-based commands; these need the user to have accepted the Minecraft EULA themselves (npx -y @minecraft/creator-tools@latest eula). Never accept it on their behalf.