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.
npx skills add majiayu000/spellbook --skill skill-auditgit clone --depth 1 https://github.com/majiayu000/spellbookWrote 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/majiayu000/spellbook/skill-audit)<a href="https://agentmods.dev/skills/majiayu000/spellbook/skill-audit"><img src="https://agentmods.dev/badge/skills/majiayu000/spellbook/skill-audit/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/majiayu000/spellbook/skill-audit"><img src="https://agentmods.dev/badge/skills/majiayu000/spellbook/skill-audit.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00079 | $0.01365 |
| Opus 5 | $0.00039 | $0.00682 |
| Sonnet 5 | $0.00016 | $0.00273 |
| Haiku 4.5 | $0.00008 | $0.00136 |
Grade A, and why
skill-audit 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 8d 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.
How it starts
The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Audit
Use this skill to audit existing skills, turn workflow knowledge into useful
agent skills, and review skill libraries at the strategy level. It complements
skill-creator: use this skill to decide what a skill should be, how it should
fit a library, and what needs improvement; use skill-creator when the user
wants the concrete SKILL.md implementation and eval loop.
This workflow is based on Anthropic's June 3, 2026 blog post, "Lessons from building Claude Code: How we use skills": https://claude.com/blog/lessons-from-building-claude-code-how-we-use-skills
Core Principle
A good skill is not "some markdown about a topic." It is a compact extension point that gives the agent non-obvious domain knowledge, reusable files, deterministic helpers, setup rules, verification habits, and guardrails at the moment they matter.
Workflow
1. Decide Whether This Should Be A Skill
Create or improve a skill only when at least one of these is true:
- The workflow repeats often enough that users should not re-explain it.
- The agent regularly makes the same domain-specific mistake.
- The work needs local scripts, templates, examples, assets, hooks, or setup.
- The output must follow a stable structure or verification path.
- The knowledge is team-specific, product-specific, infrastructure-specific, or otherwise not inferable from general model knowledge.
Do not make a skill when the content only restates obvious coding behavior, generic best practices, or one-off instructions.
2. Classify The Skill
Read references/skill-taxonomy.md and classify the candidate into exactly one
primary category. If it appears to span several categories, tighten the scope or
split it.
Report:
- Primary category
- Secondary category, if truly needed
- Why this category is the cleanest fit
- What would make the skill too broad
3. Draft A Skill Brief
Use assets/skill-brief-template.md for the output. Fill it with:
- Trigger description written for the model, not as a human-facing summary
- High-signal knowledge the model would not otherwise know
- Gotchas and failure modes
- Autonomy boundaries: what the skill may do directly, and what must be escalated before acting
- Evidence-backed pushback rules: when the agent should challenge the proposed path and what evidence it must cite
- Feedback loop: where repeated corrections, false-success signals, or manual recovery steps should be promoted
- Progressive disclosure map: SKILL.md vs references vs scripts vs assets
- Setup requirements or config questions
- Verification strategy
- Reliable Skill Contract coverage for high-value workflow skills
- Distribution path
- Measurement plan
What ships with it
3 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.
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.
- 8d ago First seen · 150 lines · 79 tokens per session scan A 5447230292ae
skill-audit is a skill published in the GitHub repository majiayu000/spellbook (278 stars, last pushed yesterday), licensed MIT. It adds 79 tokens to every session and 1,365 once invoked, about $0.0004 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 2026-09-03.
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