claude-code-plugin-development

claude-code-plugin-development is a skill for Claude Code from dwmkerr/claude-toolkit. It costs 54 tokens per session (1,473 once invoked), scanned B, original, MIT.

A guide for building distributable Claude Code plugins that package commands, agents, skills, hooks, and server configurations together.

In plain words
What is it for?
Use it to create, bundle, install, update, and troubleshoot Claude Code plugins.
Why use it?
It explains the required folder structure, manifest, installation steps, and debugging details so plugin parts are not placed or configured incorrectly.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: reads .claude/ paths; mentions .claude-plugin; mentions subagents.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the toolkit plugin — 15 skills, 3 commands, 1 agent shipped together

Good fit Use it to create, bundle, install, update, and troubleshoot Claude Code plugins.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add dwmkerr/claude-toolkit
Claude Code
/plugin install toolkit

Made for: Claude Code.

Or install toolkit, the plugin that ships this one along with the rest of its 15 skills, 3 commands, 1 agent.

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.

agentmods badge for claude-code-plugin-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/dwmkerr/claude-toolkit/claude-code-plugin-development/github.svg)](https://agentmods.dev/skills/dwmkerr/claude-toolkit/claude-code-plugin-development)
Your own site
<a href="https://agentmods.dev/skills/dwmkerr/claude-toolkit/claude-code-plugin-development"><img src="https://agentmods.dev/badge/skills/dwmkerr/claude-toolkit/claude-code-plugin-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.

agentmods 80×15 button for claude-code-plugin-development

Your own site · 80×15
<a href="https://agentmods.dev/skills/dwmkerr/claude-toolkit/claude-code-plugin-development"><img src="https://agentmods.dev/badge/skills/dwmkerr/claude-toolkit/claude-code-plugin-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,473 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00054 $0.01473
Opus 5.5 $0.00022 $0.00589
Sonnet 5.5 $0.00011 $0.00295
Haiku 4.5 $0.00005 $0.00147

Measured 1mo ago against content hash 23f7bc01c2a4, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade B, and why

claude-code-plugin-development scanned grade B with 1 finding 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.

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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

| user | `~/.claude/settings.json` | Personal plugins (default) |
plugins/toolkit/skills/claude-code-plugin-development/SKILL.md · 212 lines

How it starts

The opening of the file, as written. The whole thing — 212 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Claude Code Plugin Development

Create distributable plugins that bundle commands, agents, skills, hooks, MCP servers, and LSP servers.

Official docs: https://code.claude.com/docs/en/plugins-reference

Quick Reference

You MUST read these references for detailed schemas and examples:

Plugin Structure

my-plugin/
├── .claude-plugin/
│   └── plugin.json          # Required manifest
├── commands/                 # Slash commands (.md files)
├── agents/                   # Subagents (.md files)
├── skills/                   # Skills (subdirs with SKILL.md)
├── hooks/
│   └── hooks.json           # Hook configuration
├── .mcp.json                # MCP server definitions
├── .lsp.json                # LSP server configurations
└── scripts/                 # Hook and utility scripts

Important: Components go at plugin root, NOT inside .claude-plugin/. Only plugin.json belongs in .claude-plugin/.

Marketplace Structure

A marketplace can contain multiple plugins. The marketplace root has its own .claude-plugin/marketplace.json:

my-marketplace/
├── .claude-plugin/
│   └── marketplace.json     # Lists all plugins in this marketplace
├── plugins/
│   ├── plugin-a/
│   │   ├── .claude-plugin/
│   │   │   └── plugin.json
│   │   └── skills/
│   └── plugin-b/
│       ├── .claude-plugin/
│       │   └── plugin.json
│       └── commands/

marketplace.json

{
  "name": "my-marketplace",
  "owner": {
    "name": "author-name"
  },
  "plugins": [
    {
      "name": "plugin-a",
      "source": "./plugins/plugin-a",
      "description": "First plugin description",
      "version": "1.0.0"
    },
    {
      "name": "plugin-b",
      "source": "./plugins/plugin-b",
      "description": "Second plugin description",
      "version": "0.2.0"
    }
  ]
}

Read the full file on GitHub · 212 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.

  1. 1mo ago First seen · 212 lines · 54 tokens per session scan B 23f7bc01c2a4

Subscribe to this mod's changes

claude-code-plugin-development is a skill published in the GitHub repository dwmkerr/claude-toolkit (23 stars, last pushed 1mo ago), licensed MIT. It adds 54 tokens to every session and 1,473 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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