agentmods.dev

plugin-authoring

A reference guide for building Claude Code plugins, which are add-ons that extend Claude Code with commands, agents, skills, or automated actions. It covers the files, formats, examples, and checks used by these plugins.

In plain words
What is it for?
Use it when working with plugin files such as plugin.json, marketplace.json, commands, agents, skills, or hooks. It helps diagnose layouts, propose changes, validate them, and investigate problems.
Why use it?
It reduces guesswork when creating or fixing a plugin and helps catch invalid structure or configuration. It also keeps changes cautious by starting with a read-only review and asking before edits.

Skill for Claude CodeCodex

68 2mo ago A scan 51 tokens original MIT
View the source file ivan-magda/claude-code-plugin-template
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.

agentmods
npx agentmods add skills/ivan-magda/claude-code-plugin-template/plugin-authoring
Any agent
npx skills add ivan-magda/claude-code-plugin-template --skill plugin-authoring
Clone the repo
git clone --depth 1 https://github.com/ivan-magda/claude-code-plugin-template

Made for: Claude Code, Codex.

Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,584 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00051 $0.01584
Opus 5 $0.00026 $0.00792
Sonnet 5 $0.00010 $0.00317
Haiku 4.5 $0.00005 $0.00158

Measured 2d ago against content hash 9772da518554, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plugin-authoring 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 2d 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.

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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

plugins/plugin-development/skills/plugin-authoring/SKILL.md · 137 lines

How it starts

The opening of the file, as written. The whole thing — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Plugin Authoring (Skill)

You are the canonical guide for Claude Code plugin development. Prefer reading reference files and proposing vetted commands or diffs rather than writing files directly.

Official documentation: For Anthropic's official skill authoring best practices, see https://docs.claude.com/en/docs/agents-and-tools/agent-skills/best-practices

Triggers & Scope

Activate whenever context includes .claude-plugin/, plugin.json, marketplace.json, commands/, agents/, skills/, or hooks/.

Flow of Operation

  1. Diagnose current repo layout (read-only)
  2. Propose the minimal safe action (scaffold, validate, or review)
  3. Execute via /plugin-development:... commands when the user agrees
  4. Escalate to the plugin-reviewer agent for deep audits
  5. Guardrails: default to read-only; ask before edits

Checklists

Component Checklist

□ .claude-plugin/plugin.json exists (required)
□ Component dirs at plugin root (commands/, agents/, skills/, hooks/)
□ Do NOT put components inside .claude-plugin/ directory
□ Commands use kebab-case naming
□ Skills have valid frontmatter (name + description required, optional: model, allowed-tools)
□ Skills name validation:
  - Matches directory name
  - Lowercase letters, numbers, hyphens only
  - Max 64 characters
  - No reserved words ('anthropic', 'claude')
  - No XML tags
□ Hooks use ${CLAUDE_PLUGIN_ROOT} for paths (not relative paths)
□ All scripts are executable (chmod +x)

Read the full file on GitHub · 137 lines

Files

What ships with it

14 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. 2d ago First seen · 137 lines · 51 tokens per session scan A 9772da518554

Subscribe to this mod's changes

plugin-authoring is a skill published in the GitHub repository ivan-magda/claude-code-plugin-template (68 stars, last pushed 2mo ago), licensed MIT. It adds 51 tokens to every session and 1,584 once invoked, about $0.0003 per session on Opus 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.

DebuggingResearchai-codinganthropicclaude-codeclaude-code-pluginsclideveloper-tools
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