skill-creator

skill-creator is a skill for Claude Code from krishagel/geoffrey. It costs 94 tokens per session (3,990 once invoked), scanned A, original, MIT.

A skill-development workflow for creating, improving, and measuring coding-agent skills. It covers drafting instructions, testing them with example prompts, reviewing results, and iterating on the skill.

In plain words
What is it for?
Use it to create a skill, refine an existing one, design evaluation prompts, compare runs, review results, and improve the skill description.
Why use it?
It gives a repeatable way to improve an agent skill based on observed results instead of relying only on intuition. It can also help find problems in how a skill is triggered or evaluated.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions CLAUDE.md; mentions subagents.

Part of the geoffrey plugin — 33 skills, 2 commands, 7 agents, 4 hooks shipped together

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/krishagel/geoffrey/skill-creator
Any agent
npx skills add krishagel/geoffrey --skill skill-creator
Clone the repo
git clone --depth 1 https://github.com/krishagel/geoffrey

Made for: Claude Code.

Or install geoffrey, the plugin that ships this one along with the rest of its 33 skills, 2 commands, 7 agents, 4 hooks.

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/krishagel/geoffrey/skill-creator.svg)](https://agentmods.dev/skills/krishagel/geoffrey/skill-creator)
Your own site
<a href="https://agentmods.dev/skills/krishagel/geoffrey/skill-creator"><img src="https://agentmods.dev/badge/skills/krishagel/geoffrey/skill-creator.svg" alt="Measured on agentmods" height="20"></a>
Per session 94 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,990 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 5.1 $0.00094 $0.03990
Opus 5 $0.00047 $0.01995
Sonnet 5 $0.00019 $0.00798
Haiku 4.5 $0.00009 $0.00399

Measured 5d ago against content hash 8eb509702615, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, 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 5d ago.

The scan reads SKILL.md. This mod also ships 11 executable files (eval-viewer/generate_review.py, scripts/__init__.py, scripts/aggregate_benchmark.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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/skill-creator/SKILL.md · 399 lines

How it starts

The opening of the file, as written. The whole thing — 399 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.

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 some quantitative evals if there aren't any. Then explain them to the user
    • Use the eval-viewer/generate_review.py script to show the user the results, and also let them look at the quantitative metrics
  • Rewrite the skill based on feedback from the user's evaluation
  • Repeat until satisfied
  • Expand the test set and try again at larger scale

Your job is to figure out where the user is in this process and help them progress. Maybe they want to make a skill from scratch, or maybe they already have a draft and want to iterate.

Be flexible -- if the user says "I don't need to run a bunch of evaluations, just vibe with me", do that instead.

After the skill is done (order is flexible), run the skill description improver to optimize triggering.

Communicating with the user

Pay attention to context cues to understand how to phrase communication. In the default case:

  • "evaluation" and "benchmark" are borderline, but OK
  • for "JSON" and "assertion" you want to see cues from the user that they know what those things are before using them without explaining

It's OK to briefly explain terms if you're in doubt.


Creating a skill

Capture Intent

Start by understanding the user's intent. The current conversation might already contain a workflow the user wants to capture (e.g., they say "turn this into a skill"). If so, extract answers from the conversation history first -- the tools used, the sequence of steps, corrections the user made, input/output formats observed. The user may need to fill gaps, and should confirm before proceeding.

Read the full file on GitHub · 399 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. 5d ago First seen · 399 lines · 94 tokens per session scan A 8eb509702615

Subscribe to this mod's changes

skill-creator is a skill published in the GitHub repository krishagel/geoffrey (5 stars, last pushed 5mo ago), licensed MIT. It adds 94 tokens to every session and 3,990 once invoked, about $0.0005 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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