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.
/plugin marketplace add ArcBlock/agent-skills/plugin install plugin-developmentWrote 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.
[](https://agentmods.dev/skills/arcblock/agent-skills/plugin-authoring)<a href="https://agentmods.dev/skills/arcblock/agent-skills/plugin-authoring"><img src="https://agentmods.dev/badge/skills/arcblock/agent-skills/plugin-authoring/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.
<a href="https://agentmods.dev/skills/arcblock/agent-skills/plugin-authoring"><img src="https://agentmods.dev/badge/skills/arcblock/agent-skills/plugin-authoring.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00051 | $0.01589 |
| Opus 5.5 | $0.00020 | $0.00636 |
| Sonnet 5.5 | $0.00010 | $0.00318 |
| Haiku 4.5 | $0.00005 | $0.00159 |
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 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.
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.
This is a copy
98% identical to plugin-authoring — 4 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
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.anthropic.com/en/docs/agents-and-tools/agent-skills/skill-authoring-best-practices
Triggers & Scope
Activate whenever context includes .claude-plugin/, plugin.json, marketplace.json, commands/, agents/, skills/, or hooks/.
Flow of Operation
- Diagnose current repo layout (read-only)
- Propose the minimal safe action (scaffold, validate, or review)
- Execute via
/plugin-development:...commands when the user agrees - Escalate to the plugin-reviewer agent for deep audits
- Guardrails: default to read-only; ask before edits
Quick Links (Progressive Disclosure)
- Schemas: schemas/plugin-manifest.md, schemas/hooks-schema.md, schemas/marketplace-schema.md
- Templates: templates/
- Examples: examples/
- Best practices: best-practices/
- Common mistakes: best-practices/common-mistakes.md
- Testing this skill: testing-plugin-authoring.md
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)
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.
- best-practices/common-mistakes.md 6.6 KB
- best-practices/naming-conventions.md 8.2 KB
- best-practices/organization.md 9.0 KB
- examples/simple-plugin.md 2.8 KB
- examples/testing-workflow.md 4.7 KB
- schemas/hooks-schema.md 13 KB
- schemas/marketplace-schema.md 10 KB
- schemas/plugin-manifest.md 9.6 KB
- templates/agent-template.md 1.3 KB
- templates/command-template.md 599 B
- templates/marketplace-manifest.json 563 B
- templates/plugin-manifest.json 413 B
- templates/skill-template.md 1.7 KB
- testing-plugin-authoring.md 5.9 KB
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 First seen · 137 lines · 51 tokens per session scan A 89596157f200
plugin-authoring is a skill published in the GitHub repository ArcBlock/agent-skills (5 stars, last pushed 9d ago), licensed MIT. It adds 51 tokens to every session and 1,589 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 98% identical to plugin-authoring, differing in 4 lines, and is treated as a copy.
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