skill-creator

skill-creator is a skill for Claude Code, Codex from Jeomon/Operator-Use. It costs 64 tokens per session (5,163 once invoked), scanned B, original, MIT.

A guide for creating, editing, testing, and improving skills for coding agents.

In plain words
What is it for?
Use it to draft skills, write test cases, run evaluations, compare results, and refine instructions or descriptions.
Why use it?
It gives a repeatable process for checking whether a skill works well and whether its description triggers it for the right requests.

Skill for Claude CodeCodex

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/jeomon/operator-use/skill-creator
Any agent
npx skills add Jeomon/Operator-Use --skill skill-creator
Clone the repo
git clone --depth 1 https://github.com/Jeomon/Operator-Use

Made for: Claude Code, Codex.

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/jeomon/operator-use/skill-creator.svg)](https://agentmods.dev/skills/jeomon/operator-use/skill-creator)
Your own site
<a href="https://agentmods.dev/skills/jeomon/operator-use/skill-creator"><img src="https://agentmods.dev/badge/skills/jeomon/operator-use/skill-creator.svg" alt="Measured on agentmods" height="20"></a>
Per session 64 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,163 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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 $0.00064 $0.05163
Opus 5 $0.00032 $0.02582
Sonnet 5 $0.00013 $0.01033
Haiku 4.5 $0.00006 $0.00516

Measured 4d ago against content hash 642d47facad8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

skill-creator scanned grade B with 1 finding 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.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/__init__.py, scripts/aggregate_benchmark.py, scripts/package_skill.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.

Asks the agent to reveal its instructionsmediumSystem prompt leakage

Directions to print, repeat or translate the system prompt extract configuration the operator did not intend to expose.

**Reviewing results:** If no browser display, skip browser reviewer. Present results directly in conversation. Show prompt and output. If output is a file (docx, xlsx), save it and tell user where to download it. Ask fee
operator_use/builtins/skills/skill-creator/SKILL.md · 660 lines

How it starts

The opening of the file, as written. The whole thing — 660 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Creator

A skill for creating new skills and iteratively improving them.

Overview

At a high level, the process of creating a skill goes like this:

  • Decide what you want the skill to do and roughly how it should do it
  • Write a draft of the skill
  • Create a few test prompts and run claude-with-access-to-the-skill on them
  • Help the user evaluate the results both qualitatively and quantitatively
  • While the runs happen in the background, draft quantitative evals
  • Use the eval-viewer/generate_review.py script to show results
  • Rewrite the skill based on feedback from evaluation
  • Repeat until satisfied
  • Expand the test set and try again at larger scale

Your job when using this skill is to figure out where the user is in this process and help them progress through these stages.

How to Use This Skill

When the User is Starting Out

If they say "I want to make a skill for X":

  • Help narrow down what they mean
  • Write a draft
  • Write test cases
  • Figure out how they want to evaluate
  • Run all the prompts
  • Iterate based on feedback

When the User Already Has a Draft

Go straight to the eval/iterate part of the loop.

Being Flexible

If the user says "I don't need to run a bunch of evaluations, just vibe with me", that's fine too. Adjust your approach.

After the Skill is Done

Optionally run the skill description improver to optimize triggering accuracy.


Communicating with the User

The skill creator is used by people with varying familiarity with technical jargon.

Pay attention to context cues to understand how to phrase your communication:

  • "evaluation" and "benchmark" are generally OK
  • For "JSON" and "assertion", wait for clear signals the user knows what those are before using them without explanation
  • It's OK to briefly explain terms if you're unsure

Creating a Skill

Step 1: Capture Intent

Start by understanding the user's intent. If the conversation already contains a workflow to capture (e.g., "turn this into a skill"), extract answers from the history first.

Read the full file on GitHub · 660 lines

Files

What ships with it

10 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. 4d ago First seen · 660 lines · 64 tokens per session scan B 642d47facad8

Subscribe to this mod's changes

skill-creator is a skill published in the GitHub repository Jeomon/Operator-Use (40 stars, last pushed 2mo ago), licensed MIT. It adds 64 tokens to every session and 5,163 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 1 finding (asks the agent to reveal its instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

cli-docs-guidelines

Review or write CLI documentation. Enforces progressive disclosure, logical command ordering, and plain-language explanations. Use when asked to "write CLI docs", "document commands", "review CLI reference", or "update command docs".

CelestoAI/SmolVM · 50 tokens

readme-guidelines

Review or write README content for open-source projects. Enforces progressive disclosure, jargon-free language, and single-concept code examples. Use when asked to "write README", "review README", "update README", or "check docs".

CelestoAI/SmolVM · 52 tokens

unbrowse

The action engine of the internet. Unbrowse is the open-source action layer for AI agents: it learns a site's internal API routes from real browsing, then replays them as fast, cheap, indexed routes (cache hit under 200ms) instead of re-driving a browser. Capture once, replay everywhere. The default agent flow is ONE…

unbrowse-ai/unbrowse · 199 tokens

unbrowse

The action engine of the internet. Unbrowse is the open-source action layer for AI agents: it learns a site's internal API routes from real browsing, then replays them as fast, cheap, indexed routes (cache hit under 200ms) instead of re-driving a browser. Capture once, replay everywhere. The default agent flow is ONE…

unbrowse-ai/unbrowse · 199 tokens

ai-deploy

Deploy a generated project (one process or several) to agent-sandboxes with scale-to-zero: idle sandboxes pause and auto-resume (process restarted) on the next HTTP request. Use when asked to deploy, host, or preview generated code through the sandbox platform.

agent-sandbox/agent-sandbox · 59 tokens

e2b-sandbox

Create, manage, and use E2B sandboxes — run commands, manage files, use git, persist state, and configure networking. Use when building agent workflows that need isolated execution environments.

agent-sandbox/agent-sandbox · 45 tokens