Agent skill

Plugin Creator

by JuliusBrussee in JuliusBrussee/caveman-code

Scaffold a complete cave plugin bundle — generates .cave-plugin/plugin.json manifest and the standard directory structure (commands/, skills/, agents/, themes/, hooks/).

MITAuto-check passedAgent Workflows

Install Plugin Creator

skills CLI

$ npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install JuliusBrussee/caveman-code plugin-creator --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/JuliusBrussee/caveman-code.git skills-src && mkdir -p .claude/skills && cp -r skills-src/packages/coding-agent/skills/plugin-creator .claude/skills/plugin-creator && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "plugin-creator" agent skill from https://github.com/JuliusBrussee/caveman-code/tree/main/packages/coding-agent/skills/plugin-creator into .claude/skills/plugin-creator/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "plugin-creator", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/JuliusBrussee/caveman-code/tree/main/packages/coding-agent/skills/plugin-creator

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install JuliusBrussee/caveman-code plugin-creator --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/JuliusBrussee/caveman-code.git skills-src && mkdir -p .agents/skills && cp -r skills-src/packages/coding-agent/skills/plugin-creator .agents/skills/plugin-creator && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "plugin-creator" agent skill from https://github.com/JuliusBrussee/caveman-code/tree/main/packages/coding-agent/skills/plugin-creator into .agents/skills/plugin-creator/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "plugin-creator", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install JuliusBrussee/caveman-code plugin-creator --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/JuliusBrussee/caveman-code.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/packages/coding-agent/skills/plugin-creator .cursor/skills/plugin-creator && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "plugin-creator" agent skill from https://github.com/JuliusBrussee/caveman-code/tree/main/packages/coding-agent/skills/plugin-creator into .cursor/skills/plugin-creator/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "plugin-creator", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/JuliusBrussee/caveman-code.git --path packages/coding-agent/skills/plugin-creator

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install JuliusBrussee/caveman-code plugin-creator --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/JuliusBrussee/caveman-code.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/packages/coding-agent/skills/plugin-creator .gemini/skills/plugin-creator && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "plugin-creator" agent skill from https://github.com/JuliusBrussee/caveman-code/tree/main/packages/coding-agent/skills/plugin-creator into .gemini/skills/plugin-creator/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "plugin-creator", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install JuliusBrussee/caveman-code plugin-creator

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/JuliusBrussee/caveman-code.git skills-src && mkdir -p .github/skills && cp -r skills-src/packages/coding-agent/skills/plugin-creator .github/skills/plugin-creator && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "plugin-creator" agent skill from https://github.com/JuliusBrussee/caveman-code/tree/main/packages/coding-agent/skills/plugin-creator into .github/skills/plugin-creator/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "plugin-creator", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install JuliusBrussee/caveman-code plugin-creator --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/JuliusBrussee/caveman-code.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/packages/coding-agent/skills/plugin-creator .opencode/skills/plugin-creator && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "plugin-creator" agent skill from https://github.com/JuliusBrussee/caveman-code/tree/main/packages/coding-agent/skills/plugin-creator into .opencode/skills/plugin-creator/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "plugin-creator", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: plugin-creator
GitHub stars: 940
Token cost: ~1.1k tokens
SKILL.md length: 315 words
Files: 1
Skills in repo: 6
Repo updated: Aug 14, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Scaffold a complete cave plugin bundle — generates .cave-plugin/plugin.json manifest and the standard directory structure (commands/, skills/, agents/, themes/, hooks/).

Works in 6 steps: Ask for plugin details (name,… → Create .cave-plugin/plugin.json using… → Create only the sub-directories that are… → …
A user wants to create
SKILL.md covers Manifest Schema, Directory Structure, Scaffolding Steps and Publishing, plus 1 more section
Reaches github.com

What it does

Plugin Creator is an agent skill from JuliusBrussee/caveman-code. Scaffold a complete cave plugin bundle — generates .cave-plugin/plugin.json manifest and the standard directory structure (commands/, skills/, agents/, themes/, hooks/). Use when a user wants to create, publish, or package a cave plugin for the marketplace. Triggered by "create a plugin", "scaffold a plugin", "/plugin create", or "new cave plugin".

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Agent Workflows, covering Hooks and plugins. The repository describes itself as: Frozen — terminal coding agent measured at 1.93× fewer tokens than Codex CLI. Still works; active development moved to JuliusBrussee/caveman (caveman wrap). The licence is MIT.

When your agent uses it

A user wants to create
Package a cave plugin for the marketplace

Example prompts

“create a plugin”
“scaffold a plugin”
“/plugin create”
“/plugin-creator”

Requirements

Pre-approved tools (allowed-tools): read, write, edit, bash

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

Ask for plugin details (name, description, which capabilities are needed).
Create .cave-plugin/plugin.json using the schema above.
Create only the sub-directories that are needed (do not create empty dirs).
Add placeholder files for each enabled capability
Create a README.md with install instructions and a short description.
Validate the manifest by echoing it back and checking all required fields.

What it can do on your machine

Read from SKILL.md and the folder at commit 3a21be1. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves these tools, so the agent can use them without asking each time:
- read
- write
- edit
- bash
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are json).
From the folder's file list and the shell code blocks in SKILL.md.
Network
Hosts in commands or code, which the agent is likely to contact:
- github.com
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Plugin Creator loads about 1.1k tokens when it runs. Until then it costs about 91 tokens; SKILL.md has 315 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~91
When it runs · the whole SKILL.md, loaded when a task matches: ~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from JuliusBrussee/caveman-code at commit 3a21be1, republished under its MIT licence (© JuliusBrussee). 315 words, ~1,071 tokens.

Download SKILL.mdSave it as .claude/skills/plugin-creator/SKILL.md (or your agent's skills folder).

name: plugin-creator
description: Scaffold a complete cave plugin bundle — generates .cave-plugin/plugin.json manifest and the standard directory structure (commands/, skills/, agents/, themes/, hooks/). Use when a user wants to create, publish, or package a cave plugin for the marketplace. Triggered by "create a plugin", "scaffold a plugin", "/plugin create", or "new cave plugin".
allowed-tools: read, write, edit, bash
effort: low

Plugin Creator

You scaffold new cave plugins. A cave plugin is a directory published to GitHub (or any zip URL) with a .cave-plugin/plugin.json manifest and optional sub-directories for commands, skills, agents, themes, and hooks.

Manifest Schema

json

{
  "name": "my-plugin",
  "version": "0.1.0",
  "description": "A short, clear description of what this plugin does.",
  "author": "your-github-handle",
  "license": "MIT",
  "homepage": "https://github.com/your-handle/my-plugin",
  "caveVersion": ">=0.65.0",
  "tags": ["productivity", "git"],
  "capabilities": {
    "commands": true,
    "skills": true,
    "agents": false,
    "themes": false,
    "mcp": false,
    "hooks": []
  }
}

Field Rules

name: kebab-case, a-z0-9 and hyphens only. Must be unique in the marketplace.
version: semver ("major.minor.patch").
description: one sentence, plain text.
tags: free-form strings for caveman plugin search matching.
capabilities.commands: set true if commands/ directory is present.
capabilities.skills: set true if skills/ directory is present.
capabilities.agents: set true if agents/ directory is present.
capabilities.themes: set true if themes/ directory is present.
capabilities.mcp: set true if .mcp.json is present.
capabilities.hooks: array of hook entries (see below).

Hook Entry Shape

json

{ "event": "PostToolUse", "command": "hooks/post-tool-use.sh", "matcher": "Bash" }

Directory Structure

my-plugin/
├── .cave-plugin/
│   └── plugin.json          ← required
├── commands/
│   └── my-command.md        ← markdown slash commands
├── skills/
│   └── my-skill/
│       └── SKILL.md         ← skill with frontmatter
├── agents/
│   └── my-agent.md          ← agent definition markdown
├── themes/
│   └── my-theme.json        ← theme JSON (cave theme format)
├── hooks/
│   └── post-tool-use.sh     ← hook scripts (chmod +x)
├── .mcp.json                ← optional MCP server definitions
└── README.md

Scaffolding Steps

When the user asks to create a plugin, follow these steps:

Ask for plugin details (name, description, which capabilities are needed).
Create .cave-plugin/plugin.json using the schema above.
Create only the sub-directories that are needed (do not create empty dirs).
Add placeholder files for each enabled capability:
- commands/example.md with frontmatter ---\ndescription: Example command.\n---\n\n# Example\n\nDescribe what this command does.\n
- skills/example/SKILL.md with the standard skill frontmatter.
- agents/example.md with agent frontmatter.
- hooks/example.sh with #!/bin/bash\n# Hook: <event>\n and chmod +x.
Create a README.md with install instructions and a short description.
Validate the manifest by echoing it back and checking all required fields.

Publishing

After scaffolding, instruct the user to:

Push the plugin to a public GitHub repository.

Submit it to a marketplace by adding an entry to a marketplace.json:

json

{
  "plugins": [
    {
      "ref": "your-handle/my-plugin",
      "name": "my-plugin",
      "description": "...",
      "tags": ["..."],
      "version": "0.1.0"
    }
  ]
}

Users install it with: caveman plugin install your-handle/my-plugin

Example Interaction

User: "Create a plugin that adds a /summarize command and a post-save hook."

You:

Create .cave-plugin/plugin.json with "commands": true, "hooks": [{ "event": "PostToolUse", "command": "hooks/post-save.sh", "matcher": "Write" }].
Create commands/summarize.md with a summarize slash command description.
Create hooks/post-save.sh with a stub hook script.
Create README.md.
Report the file tree created.

Files

Just SKILL.md in packages/coding-agent/skills/plugin-creator of JuliusBrussee/caveman-code.

Open the folder on GitHubat commit 3a21be1

Compare with similar skills

Plugin Creator next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Plugin Creator compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Plugin Creator this skillJuliusBrussee/caveman-code	940	—	~1.1k	Automated safety check: Pass	MIT	1 mo ago
Hook Development for Claude Code Pluginsanthropics/claude-plugins-official	37k	11 repos	~4.1k	Automated safety check: Notes	Apache-2.0	today
Claude Code Agent Developmentanthropics/claude-plugins-official	37k	8 repos	~2.8k	Automated safety check: Pass	Apache-2.0	today
Claude Code Skill Developer Guidediet103/claude-code-infrastructure-showcase	10k	10 repos	~3.5k	Automated safety check: Pass	MIT	2 mo ago
Plugin Settings Patternanthropics/claude-plugins-official	37k	7 repos	~3k	Automated safety check: Pass	Apache-2.0	today
MCP Integration for Pluginsanthropics/claude-plugins-official	37k	11 repos	~3.1k	Automated safety check: Pass	Apache-2.0	today

Similar skills

Hook Development for Claude Code Plugins
anthropics/claude-plugins-official
Official
Explains how to write Claude Code plugin hooks, both prompt-based checks and bash commands, for events such as PreToolUse, Stop and SessionStart.
37k GitHub starsUsed in 11 repos~4.1k tokens
Agent WorkflowsAuto-check: notes
Claude Code Agent Development
anthropics/claude-plugins-official
Official
Explains how to write agents for Claude Code plugins: the markdown file with YAML frontmatter, trigger descriptions, model and color settings, and system prompt design.
37k GitHub starsUsed in 8 repos~2.8k tokens
Agent WorkflowsAuto-check passed
Claude Code Skill Developer Guide
diet103/claude-code-infrastructure-showcase
A guide to creating and managing Claude Code skills with auto-activation: skill-rules.json triggers, hooks, enforcement levels, YAML frontmatter and progressive disclosure.
10k GitHub starsUsed in 10 repos~3.5k tokens
Agent WorkflowsAuto-check passed
Plugin Settings Pattern
anthropics/claude-plugins-official
Official
Shows how Claude Code plugins keep per-project settings and state in .claude/plugin-name.local.md files with YAML frontmatter and a markdown body.
37k GitHub starsUsed in 7 repos~3k tokens
Agent WorkflowsAuto-check passed
MCP Integration for Plugins
anthropics/claude-plugins-official
Official
Explains how to bundle Model Context Protocol servers in a Claude Code plugin, covering config files, stdio, SSE, HTTP and WebSocket server types, and authentication.
37k GitHub starsUsed in 11 repos~3.1k tokens
Agent WorkflowsAuto-check passed
Claude Code Command Development
anthropics/claude-plugins-official
Official
Explains how to write Claude Code slash commands: Markdown files with YAML frontmatter, arguments, file references, bash context and interactive prompts.
37k GitHub starsUsed in 10 repos~4.8k tokens
Agent WorkflowsAuto-check passed

Questions about Plugin Creator

What does Plugin Creator do?

Scaffold a complete cave plugin bundle — generates .cave-plugin/plugin.json manifest and the standard directory structure (commands/, skills/, agents/, themes/, hooks/). Plugin Creator is an agent skill from JuliusBrussee/caveman-code.json manifest and the standard directory structure (commands/, skills/, agents/, themes/, hooks/).

When should I use Plugin Creator?

Plugin Creator fits situations like: A user wants to create; package a cave plugin for the marketplace.

How do I install Plugin Creator in Claude Code?

Run `npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a claude-code`. Or copy the skill folder (packages/coding-agent/skills/plugin-creator in JuliusBrussee/caveman-code) into .claude/skills/plugin-creator in your project. Claude Code loads it when a task matches its description.

How do I install Plugin Creator in Codex?

Run `npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a codex`. Or copy the skill folder (packages/coding-agent/skills/plugin-creator in JuliusBrussee/caveman-code) into .agents/skills/plugin-creator in your project. Codex loads it when a task matches its description.

Can I use Plugin Creator in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add JuliusBrussee/caveman-code --skill plugin-creator -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/plugin-creator, .gemini/skills/plugin-creator, .github/skills/plugin-creator and .opencode/skills/plugin-creator in your project.

What does Plugin Creator need to run?

SKILL.md names no scripts, command-line tools or credentials: Plugin Creator is instructions for the agent only. Its frontmatter pre-approves these tools: read, write, edit, bash.

Does Plugin Creator access the network?

SKILL.md names 1 domain. In commands or code: github.com; the agent is likely to contact it when it follows the instructions. This is read from the text; nothing was executed.

Is Plugin Creator safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Plugin Creator use?

Plugin Creator is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Plugin Creator use?

About 1.1k tokens (SKILL.md is roughly 4.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Plugin Creator?

Skills that share tags, products or a category with Plugin Creator: Hook Development for Claude Code Plugins (anthropics/claude-plugins-official, 37k stars), Claude Code Agent Development (anthropics/claude-plugins-official, 37k stars), Claude Code Skill Developer Guide (diet103/claude-code-infrastructure-showcase, 10k stars) and Plugin Settings Pattern (anthropics/claude-plugins-official, 37k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Plugin Creator?

JuliusBrussee (a GitHub user) maintains it in JuliusBrussee/caveman-code, which has 940 GitHub stars. The repository holds 6 skills in this directory. The repository was last updated on August 14, 2026.

Source: JuliusBrussee/caveman-code on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Plugin Creator

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Plugin Creator

Manifest Schema

Field Rules

Hook Entry Shape

Directory Structure

Scaffolding Steps

Publishing

Example Interaction

Files

Compare with similar skills

Similar skills

More from JuliusBrussee/caveman-code

Related

Questions about Plugin Creator