skill-creator

skill-creator is a skill for Claude Code from notque/vexjoy-agent. It costs 15 tokens per session (6,789 once invoked), scanned A, original, MIT.

A workflow for creating coding-agent skills and improving them through measured evaluation. It provides instructions for writing the skill files and checking their behavior.

In plain words
What is it for?
It helps scaffold new skills, refine existing ones, and validate their instructions with evaluations.
Why use it?
It gives skill authors a structured way to find and fix weaknesses instead of relying only on assumptions.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: agent in frontmatter; mentions CLAUDE.md; mentions subagents.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is python3 scripts/validate-skill-frontmatter.py skills/<skill-name>/SKILL.md.

Good fit It helps scaffold new skills, refine existing ones, and validate their instructions with evaluations.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/notque/vexjoy-agent
agentmods
npx agentmods add skills/notque/vexjoy-agent/skill-creator

Made for: Claude Code.

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 skill-creator

README.md
[![agentmods](https://agentmods.dev/badge/skills/notque/vexjoy-agent/skill-creator.svg)](https://agentmods.dev/skills/notque/vexjoy-agent/skill-creator)
Your own site
<a href="https://agentmods.dev/skills/notque/vexjoy-agent/skill-creator"><img src="https://agentmods.dev/badge/skills/notque/vexjoy-agent/skill-creator.svg" alt="Measured on agentmods" height="20"></a>
Per session 15 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,789 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00015 $0.06789
Opus 5 $0.00008 $0.03395
Sonnet 5 $0.00003 $0.01358
Haiku 4.5 $0.00002 $0.00679

Measured 3d ago against content hash 0eb86256455c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

skill-creator 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 3d ago.

The scan reads SKILL.md. This mod also ships 5 executable files (scripts/aggregate_benchmark.py, scripts/eval_compare.py, scripts/optimize_description.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/meta/skill-creator/SKILL.md · 657 lines

How it starts

The opening of the file, as written. The whole thing — 657 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Creator

Create skills and iteratively improve them through measurement.

Output style directive (applies to every generated skill/agent)

Generated SKILL.md and agent bodies must be written as dense informational text focused on accuracy. Minimize prose, maximize signal, no filler.

  • No motivational framing, no pep talk, no "this will help you...".
  • No repeated restatement of the same constraint in different words.
  • Prefer tables, numbered phases, and bullet lists over paragraphs.
  • Every sentence must carry information the model will act on; cut anything that is only atmosphere.
  • Explanations of "why" stay short and attached to the rule they justify -- one clause, not a paragraph.

New and edited skill files are written to the Dense-Complete Writing standard: skills/shared-patterns/dense-complete-writing.md. That file is the canonical rule; the bullets above are its application to skill scaffolding.

This is a generation constraint on the outputs of this skill, not a style note for this skill's own prose. Enforce it during the "Write the SKILL.md" phase and during any agent scaffolding.

The process:

  • Decide what the skill should do and how it should work
  • Write a draft of the skill
  • Create test prompts and run claude-with-the-skill on them
  • Evaluate the results -- both with agent reviewers and optionally human review
  • Improve the skill based on what the evaluation reveals
  • Repeat until the skill demonstrably helps

Figure out where the user is in this process and help them progress. If they say "I want to make a skill for X", help narrow scope, write a draft, write test cases, and run the eval loop. If they already have a draft, go straight to testing.


Creating a skill

Capture intent

Start by understanding what the user wants. The current conversation might already contain a workflow worth capturing ("turn this into a skill"). If so, extract:

  1. What should this skill enable Claude to do?
  2. When should this skill trigger? (what user phrases, what contexts)
  3. What is the expected output?
  4. Are the outputs objectively verifiable (code, data transforms, structured files) or subjective (writing quality, design aesthetics)? Objectively verifiable outputs benefit from test cases. Subjective outputs are better evaluated by human review.

Read the full file on GitHub · 657 lines

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. 3d ago First seen · 657 lines · 15 tokens per session scan A 0eb86256455c

Subscribe to this mod's changes

skill-creator is a skill published in the GitHub repository notque/vexjoy-agent (419 stars, last pushed 2d ago), licensed MIT. It adds 15 tokens to every session and 6,789 once invoked, about $0.0001 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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