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 agentmods add skills/mthines/agent-skills/create-skillnpx skills add mthines/agent-skills --skill create-skillgit clone --depth 1 https://github.com/mthines/agent-skillsWrote 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/mthines/agent-skills/create-skill)<a href="https://agentmods.dev/skills/mthines/agent-skills/create-skill"><img src="https://agentmods.dev/badge/skills/mthines/agent-skills/create-skill.svg" alt="Measured on agentmods" 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 | $0.00160 | $0.04012 |
| Opus 5 | $0.00080 | $0.02006 |
| Sonnet 5 | $0.00032 | $0.00802 |
| Haiku 4.5 | $0.00016 | $0.00401 |
Grade A, and why
create-skill 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 4d 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 — 371 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Create Skill
Author new agent skills — and audit existing ones — against the best practices distilled from Anthropic's official Skill authoring guide and the patterns already in this repo. Output is a complete skill directory plus the agent-skills.git symlink wiring and inventory updates.
This
SKILL.mdis a thin index. Detailed authoring rules live inrules/*.mdand load on demand. Worked examples live inreferences/*.md. Literal scaffolding templates live intemplates/*.md. Reading them all up-front would burn tokens you do not need yet — load only what the current phase asks for.
Mode Detection
Parse $ARGUMENTS (first token) and detect the mode:
| Mode | Default | Trigger |
|---|---|---|
scaffold |
yes | Default. "create", "scaffold", "new skill", or no mode argument. |
review |
"review", "audit", "check this skill", or $0 == "review". |
|
upgrade |
"upgrade", "split", "convert to multi-file", or $0 == "upgrade". |
|
diagnose |
"diagnose", "why did miss this", or $0 == "diagnose". |
If the user typed a path or skill name as $ARGUMENTS, treat it as the
target for review/upgrade/diagnose; for scaffold it is the proposed
skill name.
State the detected mode and target in one line before continuing. Example:
Mode: scaffold
Target: skills/<category>/<proposed-name>/
Scaffold Workflow (default)
A six-phase pipeline. Each phase has a gate; do not proceed until it passes.
| Phase | Name | Gate |
|---|---|---|
| 0 | Requirements | User confirmed name, description, modes, structure choice |
| 1 | Structure decision | Single-file vs multi-file decided with reasoning |
| 2 | Frontmatter draft | Name + description + flags pass validation |
| 3 | File generation | All planned files written, none over budget |
| 4 | Wiring & inventories | Symlinks created (if local-dev), CLAUDE.md + README.md updated |
| 5 | Self-check | Every checklist item in rules/quality-checklist.md passes |
What ships with it
21 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.
- references/good-vs-bad-examples.md 7.6 KB
- references/skill-archetypes.md 12 KB
- rules/anti-patterns.md 6.2 KB
- rules/description-writing.md 4.0 KB
- rules/diagnose-mode.md 28 KB
- rules/diagnostic-surface.md 10 KB
- rules/frontmatter.md 7.4 KB
- rules/invocation-control.md 5.3 KB
- rules/progressive-disclosure.md 5.5 KB
- rules/quality-checklist.md 4.7 KB
- rules/repository-conventions.md 5.2 KB
- rules/review-lens-contract.md 6.7 KB
- rules/self-improvement-loop-pattern.md 8.4 KB
- rules/structure-decision.md 4.7 KB
- rules/token-economics.md 4.4 KB
- templates/diagnostic-surface.template.md 3.2 KB
- templates/lens.md 849 B
- templates/reference.md 408 B
- templates/rule.md 920 B
- templates/SKILL.minimal.md 1.4 KB
- templates/SKILL.multi-file.md 2.2 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.
- 4d ago First seen · 371 lines · 160 tokens per session scan A 11376f301436
create-skill is a skill published in the GitHub repository mthines/agent-skills (12 stars, last pushed today), licensed MIT. It adds 160 tokens to every session and 4,012 once invoked, about $0.0008 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 2026-08-31.
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