Minecraft Custom Mod Builder

Minecraft Custom Mod Builder: Deterministically generate and preview Minecraft Bedrock, Bedrock skin pack, Fabric, and NeoForge mod artifacts from structured specs. Use when an agent needs minecraft custom mod builder, create installable minecraft bedrock add ons (.mcaddon) from a simple description, build java mods for fabric and neoforge and download the .jar, design custom swords, pickaxes, create mod project, target platform, mod id through AgentPMT-hosted remote tool calls.

AgentPMT@agentpmt

Install

openclaw skills install @agentpmt/minecraft-custom-mod-builder

Minecraft Custom Mod Builder

Freshness

Last updated: 2026-06-23.

If the current date is more than 7 days after the last updated date, reinstall this skill from skills.sh or ClawHub before relying on endpoints, schemas, setup steps, or examples.

What This Tool Does

Create your own custom Minecraft mods and add-ons — no coding required. Just describe what you want to add to the game, from a flaming sword or a glowing ore to a rideable mob, a custom skin pack, or a whole new dimension, and get back a ready-to-install file in seconds. Build for Minecraft Bedrock (.mcaddon) and Java with Fabric and NeoForge (.jar). Create items, weapons, tools, armor, blocks, ores, food, mobs, bosses, biomes, structures, recipes, loot tables, enchantments, trades, and special in-game behavior — each with its own custom texture from a color, your own artwork, or generated pixel art. Preview every icon before you install, and download editable source so you can keep building. Perfect for creators, streamers, server owners, and players who want their own Minecraft content fast.

Product Instructions

Minecraft Mod Builder

Generate deterministic Minecraft Bedrock, Fabric, and NeoForge mod artifacts from structured specifications. This tool does not call an LLM, does not accept prompts, and does not require user credentials.

Two Rules That Will Save You Many Retries

Rule 1 — One ItemSpec equals one in-game item

A single ItemSpec produces one in-game item. The fields damage, durability, max_stack_size, nutrition, tool, armor, food, block_placer, entity_placer, enchantable, repairable, digger, cooldown, glint, rarity, dyeable, and component_overrides all attach to the same item. A weapon does not need a separate entity or a separate "damage item." A sword does not need a partner "enchantment item." You ship one item; this tool wires up every relevant Minecraft component on that item from the fields above.

Do not split one weapon idea across many items[] entries. Do not duplicate a weapon and call one copy "damage" and another "durability." That is the most common source of bloated, broken submissions.

Rule 2 — Every visible asset requires a texture

Items, blocks, entities, particles, named texture assets, machines, storage, and skin-pack skins must each carry a texture with one of these three sources:

source_base64 — base64-encoded PNG or JPEG bytes (max 1024×1024, max 5 MB).
source_file_id — a File Manager file_id for a user-uploaded image.
color_hex — an explicit #RRGGBB color. Only item_kind in {tool, weapon} (with tool_type) and the dedicated texture_kind in {block, entity} paths produce a recognizable sprite (sword/pickaxe/axe/shovel/hoe; shaded block face; humanoid silhouette). For every other kind — generic, food, fuel, projectile, block_placer, entity_placer, armor, particles, machines, storage — color_hex renders only as a flat colored 16×16 square. That is appropriate for raw materials (ingots, dust, gems) but looks like a missing texture for armor/food/machines. Use source_base64 or source_file_id whenever the item's identity is visual (armor, food, machines, storage, projectiles). Tool/weapon color_hex requires tool_type; otherwise rejected.

A spec that omits the texture binding is rejected at validation with MINECRAFT_VISIBLE_ASSET_TEXTURE_REQUIRED. There is no procedural blob fallback. If you want the user to see something, you supply the texture.

Armor pieces must ship a real PNG. item_kind="armor" rejects color_hex-only textures (MINECRAFT_ARMOR_TEXTURE_REQUIRES_IMAGE) — the procedural sprite for armor is a flat colored square, which looks broken on the wearer model and in inventory. Supply source_base64 or source_file_id for every helmet/chestplate/leggings/boots.

Authoring textures with the Icon Generator + `pixelize_to`

The canonical way to author textures for items, blocks, entities, and particles is the Icon Generator (/product-icon-generator). Render at the exact target grid in pixel_art_mode=true — 16×16 for items and blocks, 64×64 for entities and skin packs — and pipe the returned file_id straight into this texture's source_file_id. Detailed recipes live in agent_instructions/minecraft_texture_agent.md.

When the texture originates outside the Icon Generator (AI image creator, user upload, third-party source), use the ingest-side safety net by setting texture.pixelize_to and optionally texture.palette_colors. Both fields are opt-in (None by default) so existing bindings remain byte-identical. Example: {"texture": {"source_file_id": "abc...", "pixelize_to": 16, "palette_colors": 8}} nearest-neighbor downscales the input to 16×16 and quantizes it to an 8-color palette with dithering disabled, producing crisp pixel-art output regardless of how the source was made. Failures surface as MINECRAFT_TEXTURE_PIXELIZE_FAILED.

Recommended defaults unless you have a specific reason to deviate: items/blocks → pixelize_to: 16, palette_colors: 8; entities/skins → pixelize_to: 64, palette_colors: 16; particles → pixelize_to: 16, palette_colors: 4. The color_hex binding path is unaffected — it already produces crisp procedural sprites.

Quick Recipes

Diamond sword

json

{"items":[{"item_id":"flame_sword","display_name":"Flame Sword","item_kind":"weapon","tool_type":"sword","tool_tier":"diamond","damage":7,"texture":{"color_hex":"#ff5522"}}]}

Iron pickaxe

json

{"items":[{"item_id":"iron_pickaxe","display_name":"Iron Pickaxe","item_kind":"tool","tool_type":"pickaxe","tool_tier":"iron","texture":{"color_hex":"#cccccc"}}]}

Custom-texture armor set

json

{"items":[
  {"item_id":"set_helmet","display_name":"Set Helmet","item_kind":"armor","tool_tier":"diamond","armor":{"slot":"head","protection":3,"toughness":2},"texture":{"source_file_id":"<file_id>","pixelize_to":16,"palette_colors":8}},
  {"item_id":"set_chest","display_name":"Set Chest","item_kind":"armor","tool_tier":"diamond","armor":{"slot":"chest","protection":8,"toughness":2},"texture":{"source_file_id":"<file_id>","pixelize_to":16,"palette_colors":8}},
  {"item_id":"set_legs","display_name":"Set Legs","item_kind":"armor","tool_tier":"diamond","armor":{"slot":"legs","protection":6,"toughness":2},"texture":{"source_file_id":"<file_id>","pixelize_to":16,"palette_colors":8}},
  {"item_id":"set_boots","display_name":"Set Boots","item_kind":"armor","tool_tier":"diamond","armor":{"slot":"feet","protection":3,"toughness":2},"texture":{"source_file_id":"<file_id>","pixelize_to":16,"palette_colors":8}}
]}

Block + matching ore

json

{"blocks":[{"block_id":"raw_obsidium","display_name":"Raw Obsidium","block_kind":"basic","hardness":3.0,"resistance":12,"texture":{"color_hex":"#2a0033"}}],"worldgen":[{"feature_id":"obsidium_ore","feature_kind":"ore_feature","block_id":"raw_obsidium","vein_size":4,"count_per_chunk":2,"min_y":0,"max_y":48,"biomes":["minecraft:overworld"]}]}

Passive entity (sheep-like)

json

{"entities":[{"entity_id":"cloudling","display_name":"Cloudling","entity_kind":"passive_mob","health":12,"texture":{"source_file_id":"<file_id>","pixelize_to":64,"palette_colors":16}}]}

Sword with on-hit fire event

json

{"items":[{"item_id":"flame_sword","display_name":"Flame Sword","item_kind":"weapon","tool_type":"sword","tool_tier":"diamond","damage":7,"texture":{"color_hex":"#ff5522"}}],"events":[{"event_id":"flame_sword_ignite","event_kind":"on_item_hit_entity","conditions":[{"condition_kind":"held_item","identifier":"modid:flame_sword"}],"actions":[{"action_kind":"set_on_fire","duration_ticks":120}]}]}

Skin pack (Bedrock)

json

{"action":"create_mod_project","target_platform":"bedrock_skinpack","mod_id":"blue_pack","mod_name":"Blue Pack","skin_pack":{"pack_id":"blue_pack","display_name":"Blue Pack","skins":[{"skin_id":"blue_hero","display_name":"Blue Hero","texture":{"source_base64":"<base64-encoded 64x64 PNG>"}}]}}

Skin pack textures must be exactly 64×64 PNG.

Verify Every Generation

Always follow create_mod_project with a render_preview_image call against the just-generated mod_id. The preview confirms the icon renders correctly before you ask the user to install. If the preview looks like a flat colored square or the wrong tool sprite, you forgot item_kind, tool_type, or both.

Common Mistakes

Mistake	What happens now
`item_kind="generic"` on a weapon with `damage` set	Rejected: `MINECRAFT_ITEM_KIND_REQUIRES_PRESET`
`item_kind="tool"` without `tool_type`	Rejected: `MINECRAFT_ITEM_KIND_REQUIRES_PRESET`
`item_kind="weapon"` with `tool_type="pickaxe"`	Rejected: weapon requires `sword` or `custom`
`item_kind="armor"` without `armor` or `wearable`	Rejected: `MINECRAFT_ITEM_KIND_REQUIRES_PRESET`
`item_kind="food"` without `food` preset or `nutrition`	Rejected: `MINECRAFT_ITEM_KIND_REQUIRES_PRESET`
`texture` omitted on any visible asset	Rejected: `MINECRAFT_VISIBLE_ASSET_TEXTURE_REQUIRED`
`texture: {}` with no `color_hex`, `source_base64`, or `source_file_id`	Rejected: `MINECRAFT_TEXTURE_SOURCE_REQUIRED`
`item_kind="armor"` with `texture: {color_hex: ...}` only	Rejected: `MINECRAFT_ARMOR_TEXTURE_REQUIRES_IMAGE`
`pixelize_to` set to a value other than 16, 32, 64, or 128	Rejected: schema validation
Source image fails to decode during pixelize	`MINECRAFT_TEXTURE_PIXELIZE_FAILED`
Pickaxe specced to "break any block" but only breaks a few	Add `tool.break_all_blocks: true`
Feature appears in the wrong platform build	Set `enabled_platforms: ["bedrock"]` (or fabric/neoforge)
Block `drops` references an item id that doesn't exist	Rejected with `MINECRAFT_SPEC_VALIDATION_FAILED`
Multiple `items[]` entries for one weapon	Two items in inventory; collapse to one ItemSpec
`on_item_hit_entity` without a `held_item` condition	Fires for every hit; add a `held_item` condition
`command_id` shadowing a Minecraft command (e.g. `give`, `tp`)	Reject or behavior conflict; pick a unique id

Supported Platforms

bedrock: Minecraft Bedrock add-on generation. Produces .mcaddon installables and Mojang Minecraft Creator Tools validation reports.
fabric: Minecraft Java Fabric generation. Produces source zips and optional built jars.
neoforge: Minecraft Java NeoForge generation. Produces source zips and optional built jars.
bedrock_skinpack: Bedrock skin pack generation. Produces .mcpack files.
forge is retired. Use neoforge.

Texture Binding Fields (BindingTextureSpec)

Every visible asset's texture field is a BindingTextureSpec. Required: exactly one of color_hex, source_base64, or source_file_id.

Optional ingest-side transforms:

pixelize_to: integer in {16, 32, 64, 128}. Nearest-neighbor downscales the source image to that square dimension before baking.
palette_colors: integer 2-256. Quantizes the (post-pixelize) image to the requested palette size via Fast Octree (no dither).

Both fields default to None (no transform). They only affect the source_base64 and source_file_id paths; color_hex renders are unaffected.

Actions

list_capabilities: Return the supported feature/event/action matrix for a target platform.
validate_mod_project: Validate a spec without writing artifacts. Use to check coherence before paying for create_mod_project.
create_mod_project: Validate + generate the mod artifact. Returns source zip and/or installable archive paths.
render_preview_image: Render an enlarged preview of a generated texture/icon for verification.

Output Behavior

Bedrock installable returns a .mcaddon and validation report. With validate_output=true, Mojang Minecraft Creator Tools validates the generated add-on.
Fabric/NeoForge installable returns a jar when build_jar=true; otherwise use source for source zips only.
render_preview_image returns a preview artifact with a PNG file_id, signed URL, and image metadata.
Artifacts expire according to the File Manager storage policy.

When To Use

Use this skill for Minecraft Custom Mod Builder on AgentPMT.
Use it when an agent needs this specific tool's behavior, schema, inputs, outputs, and invocation shape.
Search and activation keywords: minecraft custom mod builder, create installable minecraft bedrock add ons (.mcaddon) from a simple description, build java mods for fabric and neoforge and download the .jar, design custom swords, pickaxes, create mod project, target platform, mod id.
Supported action names: create_mod_project, list_capabilities, render_preview_image, validate_mod_project.

Use Cases

Create installable Minecraft Bedrock add-ons (.mcaddon) from a simple description
Build Java mods for Fabric and NeoForge and download the .jar
Design custom swords
pickaxes
tools
and armor with their own textures
Add new blocks
ores
and crops with world generation
Create custom mobs from passive animals to hostile bosses and tameable pets
Make Bedrock skin packs (.mcpack) for a fresh character look
Give items special behavior like a sword that sets enemies on fire
Add custom crafting recipes
loot tables
enchantments
and villager trades

Categories And Industries

No categories or industry tags are published for this tool.

Actions And Schema

Complete generated action schema: ./schema.md. Supported action count: 4. x402 availability: not enabled for this product.

create_mod_project (action slug: create-mod-project): Generate mod artifacts and upload them to File Manager. Returns artifact file_ids, signed URLs, generated file manifests, validation results, install instructions, warnings, and build reports. Always follow this call with render_preview_image to confirm the icon before asking the user to install. Price: 25 credits. Parameters: advanced_resources, allow_experimental_bedrock_features, assets, build_jar, compatibility_mode, description, features, include_file_preview, plus 8 more.
list_capabilities (action slug: list-capabilities): Return supported platforms, pinned dependencies, feature kinds, event kinds, action kinds, output artifacts, unsupported categories, the v2 schema version, the major capability matrix, and the Bedrock component registry derived from the pinned Mojang Bedrock Samples archive. Price: 25 credits. Parameters: target_platform.
render_preview_image (action slug: render-preview-image): Render an enlarged PNG preview for an item/block/entity texture and upload it to File Manager. Three modes: (1) spec preview — pass target_platform, mod_id, mod_name, features; (2) archive preview — pass source_archive_file_id; (3) direct image preview — pass preview_source_file_id. Returns a preview artifact with PNG file_id, signed URL, and image metadata. Price: 25 credits. Parameters: advanced_resources, allow_experimental_bedrock_features, assets, compatibility_mode, description, features, minecraft_version, mod_id, plus 10 more.
validate_mod_project (action slug: validate-mod-project): Validate either a structured mod specification (spec mode) or a previously generated source archive (archive mode). Spec mode: provide target_platform, mod_id, mod_name, features (or skin_pack for skinpacks). Archive mode: provide source_archive_file_id. Returns a validation report with error codes and warnings; does NOT write artifacts. Price: 25 credits. Parameters: advanced_resources, allow_experimental_bedrock_features, assets, compatibility_mode, description, features, minecraft_version, mod_id, plus 5 more.

Live Schema And Examples

Use the compact schema above for ordinary calls. Before a new production integration, or whenever parameters, enum values, nested objects, outputs, or examples are unclear, fetch live details first.

Exact schema: call agentpmt-tool-search-and-execution with action: "get_schema", and tool_id: "minecraft-custom-mod-builder".
Detailed examples: call agentpmt-tool-search-and-execution with action: "get_instructions" and tool_id: "minecraft-custom-mod-builder", or call this product with action: "get_instructions" when the product tool is already selected.
Treat returned live schema and instructions as more specific than this generated summary.

MCP schema lookup through the main AgentPMT MCP server:

json

{
  "method": "tools/call",
  "params": {
    "name": "AgentPMT-Tool-Search-and-Execution",
    "arguments": {
      "action": "get_schema",
      "tool_id": "minecraft-custom-mod-builder"
    }
  }
}

For live examples, keep the same MCP tool and use these arguments:

json

{
  "action": "get_instructions",
  "tool_id": "minecraft-custom-mod-builder"
}

Authenticated AgentPMT REST schema lookup body:

json

{
  "name": "agentpmt-tool-search-and-execution",
  "parameters": {
    "action": "get_schema",
    "tool_id": "minecraft-custom-mod-builder"
  }
}

Authenticated AgentPMT REST live examples body:

json

{
  "name": "agentpmt-tool-search-and-execution",
  "parameters": {
    "action": "get_instructions",
    "tool_id": "minecraft-custom-mod-builder"
  }
}

Call This Tool

Product slug: minecraft-custom-mod-builder

Marketplace page: https://www.agentpmt.com/marketplace/minecraft-custom-mod-builder

AgentPMT account route: first use ../agentpmt-account-mcp-rest-api-setup to connect the main MCP server or REST API for an Agent Group where this tool is enabled.
x402 route: not enabled for this product.
AgentPMT overview: use ../what-is-agentpmt for marketplace, Agent Group, workflow, MCP, REST, and payment concepts.

If those setup skills are not installed beside this product skill, use the downloads below.

Core AgentPMT setup skills:

What AgentPMT is: ../what-is-agentpmt
- ClawHub page: https://clawhub.ai/agentpmt/what-is-agentpmt
- OpenClaw install: openclaw skills install what-is-agentpmt
- skills.sh install: npx skills add AgentPMT/agent-skills --skill what-is-agentpmt
AgentPMT account MCP/REST setup: ../agentpmt-account-mcp-rest-api-setup
- ClawHub page: https://clawhub.ai/agentpmt/agentpmt-account-mcp-rest-api-setup
- OpenClaw install: openclaw skills install agentpmt-account-mcp-rest-api-setup
- skills.sh install: npx skills add AgentPMT/agent-skills --skill agentpmt-account-mcp-rest-api-setup

skills.sh install script:

bash

npx skills add AgentPMT/agent-skills --skill what-is-agentpmt
npx skills add AgentPMT/agent-skills --skill agentpmt-account-mcp-rest-api-setup

MCP call shape after the main AgentPMT MCP server is connected:

json

{
  "method": "tools/call",
  "params": {
    "name": "Minecraft-Custom-Mod-Builder",
    "arguments": {
      "action": "create_mod_project",
      "advanced_resources": [
        {}
      ],
      "allow_experimental_bedrock_features": true,
      "assets": {},
      "build_jar": true,
      "compatibility_mode": "strict",
      "description": "example description",
      "features": {
        "animation_controllers": [
          {}
        ],
        "animations": [
          {}
        ],
        "biomes": [
          {}
        ],
        "blocks": [
          {
            "block_id": "example block id",
            "block_kind": "basic",
            "collision_box": {},
            "component_overrides": [
              {}
            ],
            "crafting_table": false,
            "crop": {},
            "custom_components": [
              "example custom component"
            ],
            "description": "example description"
          }
        ],
        "commands": [
          {
            "actions": [
              {}
            ],
            "command_id": "example command id",
            "command_kind": "simple_command",
            "description": "example description",
            "enabled_platforms": [
              "bedrock"
            ],
            "parameters": [
              {}
            ],
            "permission_level": "any"
          }
        ],
        "damage_types": [
          {}
        ],
        "dimensions": [
          {}
        ],
        "effects": [
          {}
        ]
      },
      "include_file_preview": true
    }
  }
}

Use the exact tool name returned by tools/list; the name above is the expected readable form.

Authenticated AgentPMT REST call body:

json

{
  "name": "minecraft-custom-mod-builder",
  "parameters": {
    "action": "create_mod_project",
    "advanced_resources": [
      {}
    ],
    "allow_experimental_bedrock_features": true,
    "assets": {},
    "build_jar": true,
    "compatibility_mode": "strict",
    "description": "example description",
    "features": {
      "animation_controllers": [
        {}
      ],
      "animations": [
        {}
      ],
      "biomes": [
        {}
      ],
      "blocks": [
        {
          "block_id": "example block id",
          "block_kind": "basic",
          "collision_box": {},
          "component_overrides": [
            {}
          ],
          "crafting_table": false,
          "crop": {},
          "custom_components": [
            "example custom component"
          ],
          "description": "example description"
        }
      ],
      "commands": [
        {
          "actions": [
            {}
          ],
          "command_id": "example command id",
          "command_kind": "simple_command",
          "description": "example description",
          "enabled_platforms": [
            "bedrock"
          ],
          "parameters": [
            {}
          ],
          "permission_level": "any"
        }
      ],
      "damage_types": [
        {}
      ],
      "dimensions": [
        {}
      ],
      "effects": [
        {}
      ]
    },
    "include_file_preview": true
  }
}

Use the setup skill for the account connection details before making REST calls.

Response Handling

Treat the returned JSON as the source of truth for this tool call.
If the response includes warnings or correction targets, apply them before retrying.
If the response includes a passed or success-style boolean, use it as the workflow gate.
If validation fails or the response shape is unclear, call get_schema or get_instructions before retrying.
If create_mod_project fails, preserve the request parameters and retry only after fixing schema, auth, or payment errors.

Security

Do not place account secrets, wallet private keys, mnemonics, signatures, or payment headers in prompts or logs.
Keep tool inputs scoped to the minimum content needed for the task.
Use the setup skills for credential handling; this product skill only defines product-specific behavior.

AgentPMT Reference

What AgentPMT is: ../what-is-agentpmt (ClawHub: what-is-agentpmt, page: https://clawhub.ai/agentpmt/what-is-agentpmt; skills.sh: npx skills add AgentPMT/agent-skills --skill what-is-agentpmt)
AgentPMT account MCP/REST setup: ../agentpmt-account-mcp-rest-api-setup (ClawHub: agentpmt-account-mcp-rest-api-setup, page: https://clawhub.ai/agentpmt/agentpmt-account-mcp-rest-api-setup; skills.sh: npx skills add AgentPMT/agent-skills --skill agentpmt-account-mcp-rest-api-setup)
Marketplace product: https://www.agentpmt.com/marketplace/minecraft-custom-mod-builder
AgentPMT main MCP server: https://api.agentpmt.com/mcp/
AgentPMT REST invoke endpoint: https://api.agentpmt.com/products/purchase

Minecraft Custom Mod Builder

Install

Minecraft Custom Mod Builder

Freshness

What This Tool Does

Product Instructions

Minecraft Mod Builder

Two Rules That Will Save You Many Retries

Rule 1 — One ItemSpec equals one in-game item

Rule 2 — Every visible asset requires a texture

Authoring textures with the Icon Generator + pixelize_to

Quick Recipes

Diamond sword

Iron pickaxe

Custom-texture armor set

Block + matching ore

Passive entity (sheep-like)

Sword with on-hit fire event

Skin pack (Bedrock)

Verify Every Generation

Common Mistakes

Supported Platforms

Texture Binding Fields (BindingTextureSpec)

Actions

Output Behavior

When To Use

Use Cases

Related Product Skills

Categories And Industries

Actions And Schema

Live Schema And Examples

Call This Tool

Response Handling

Security

AgentPMT Reference

Authoring textures with the Icon Generator + `pixelize_to`