What is blockbench-plugins?

A guide and toolkit for writing JavaScript extensions for Blockbench, a 3D modeling application. It covers adding commands and panels, changing models, and importing or exporting formats.

Use it to create or debug Blockbench plugins, including actions, dialogs, panels, toolbars, model edits, animations, and custom file formats.

It gives an agent the documented patterns needed to connect a custom extension to Blockbench's menus, interface, model data, and events.

blockbench-plugins — Skill for Claude Code by jasonjgardner

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add jasonjgardner/blockbench-mcp-project --skill blockbench-development

Clone the repo

git clone --depth 1 https://github.com/jasonjgardner/blockbench-mcp-project

Made for: Claude Code.

Or install blockbench-mcp, the plugin that ships this one along with the rest of its 15 skills, 5 commands, 1 agent, 2 MCP servers.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/jasonjgardner/blockbench-mcp-project/blockbench-development/github.svg)](https://agentmods.dev/skills/jasonjgardner/blockbench-mcp-project/blockbench-development)

Your own site

<a href="https://agentmods.dev/skills/jasonjgardner/blockbench-mcp-project/blockbench-development"><img src="https://agentmods.dev/badge/skills/jasonjgardner/blockbench-mcp-project/blockbench-development/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/jasonjgardner/blockbench-mcp-project/blockbench-development"><img src="https://agentmods.dev/badge/skills/jasonjgardner/blockbench-mcp-project/blockbench-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 87 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,268 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00087	$0.03268
Opus 5.5	$0.00035	$0.01307
Sonnet 5.5	$0.00017	$0.00654
Haiku 4.5	$0.00009	$0.00327

Measured 1mo ago against content hash 8fad1b34bccd, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

blockbench-plugins scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

The scan reads SKILL.md. This mod also ships 2 executable files (assets/format_plugin.js, assets/plugin_template.js), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/blockbench-development/SKILL.md · 464 lines

How it starts

The opening of the file, as written. The whole thing — 464 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Blockbench Plugin Development

Overview

Blockbench runs on desktop and the web, exposing host APIs and bundled rendering/UI libraries to plugins. Verify the target host version and its types before choosing APIs; plugin variable isolation does not imply unrestricted native-module or filesystem access. Prefer the current generated API reference and the target checkout when older wiki examples disagree with the host. Set variant and min_version to the environments actually verified.

For model format decisions, UV units, rig distinctions and export handoffs, see format and delivery guidance. A format feature flag advertises host behavior; it does not implement missing validation or runtime serialization in a custom codec.

Quick Reference

Task	Approach
Create clickable command	`new Action()` - add to menus/toolbars
Show form/dialog	`new Dialog()` with form fields
Add sidebar panel	`new Panel()` with Vue component
Modify model elements	Use `Undo.initEdit()` → modify → `Undo.finishEdit()`
Custom import/export	`new Codec()` + `new ModelFormat()`
React to changes	`Blockbench.on('event_name', callback)`

Plugin File Structure

plugins/
└── my_plugin/
    ├── my_plugin.js      # Main file (required, ID must match filename)
    ├── about.md          # Extended docs (optional)
    └── icon.png          # 48x48 icon (optional)

Plugin Registration Template

(function() {
    // Store references for cleanup
    let myAction, myPanel, myDialog, eventCallback;
    
    Plugin.register('my_plugin', {
        title: 'My Plugin',
        author: 'Author Name',
        description: 'Short description',
        icon: 'extension',            // Material icon name
        version: '1.0.0',
        variant: 'both',              // 'desktop', 'web', or 'both'
        min_version: '4.8.0',
        tags: ['Utility'],
        
        onload() {
            // Initialize all components here
        },
        
        onunload() {
            // CRITICAL: Delete ALL components here
        },
        
        oninstall() {
            Blockbench.showQuickMessage('Installed!');
        }
    });
})();

Read the full file on GitHub · 464 lines

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

1mo ago Changed · +17 lines 8fad1b34bccd
2mo ago First seen · 447 lines · 87 tokens per session scan A 4181fb1b2fbd

Subscribe to this mod's changes

blockbench-plugins is a skill published in the GitHub repository jasonjgardner/blockbench-mcp-project (27 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 87 tokens to every session and 3,268 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Game development blockbench blockbench-plugin mcp

blockbench-plugins next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
blockbench-pluginsjasonjgardner/blockbench-mcp-project	Skill	27	1mo ago	Apache-2.0	A	87	Claude Code
blockbench-mcp-modelingsosadly/blockbench-mcp	Skill	65	9d ago	MIT	A	150	Claude Code, Codex
img2blockbenchorca-gamedev/img2blockbench	Skill	30	16d ago	MIT	A	106	Codex
playtest-reportDonchitos/Claude-Code-Game-Studios	Skill	36k	18d ago	MIT	A	20	Claude Code
godot-signals-groupsgamedev-skills/awesome-gamedev-agent-skills	Skill	6.9k	9d ago	Apache-2.0	A	95	Claude Code
motionOpenDCAI/GameFactory-3A	Skill	1.0k	8d ago	Apache-2.0	A	0	Claude Code, Codex
unity-addressablesBesty0728/Unity-Skills	Skill	1.9k	yesterday	MIT	A	25	Claude Code, Codex