agentmods.dev

ck:skill-creator

Instructions for creating or updating Codex skills, which are reusable guidance packages that teach a coding agent how to perform specific tasks.

In plain words
What is it for?
Use it to design new skills, improve existing ones, add references or scripts, and prepare skills for benchmark testing.
Why use it?
It helps turn a recurring workflow into a clear, reusable skill with suitable instructions, scripts, and supporting files.

Skill for Claude CodeCodex

88 4d ago A scan 37 tokens original MIT
View the source file manhvann/codexkit
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/manhvann/codexkit/skill-creator
Any agent
npx skills add manhvann/codexkit --skill skill-creator
Clone the repo
git clone --depth 1 https://github.com/manhvann/codexkit

Made for: Claude Code, Codex.

Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,057 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 $0.00037 $0.01057
Opus 5 $0.00018 $0.00528
Sonnet 5 $0.00007 $0.00211
Haiku 4.5 $0.00004 $0.00106

Measured 2d ago against content hash 7edd41dee043, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ck: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 2d ago.

The scan reads SKILL.md. This mod also ships 4 executable files (scripts/encoding_utils.py, scripts/init_skill.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.

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.

.agents/skills/skill-creator/SKILL.md · 120 lines

How it starts

The opening of the file, as written. The whole thing — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Creator

Create effective, benchmark-optimized Codex skills using progressive disclosure.

Core Principles

  • Skills are practical instructions, not documentation
  • Each skill teaches Codex how to perform tasks, not what tools are
  • Multiple skills activate automatically based on metadata quality
  • Progressive disclosure: Metadata → SKILL.md → Bundled resources

Quick Reference

Resource Limit Purpose
Description <200 chars Auto-activation trigger
SKILL.md <150 lines Core instructions
Each reference <150 lines Detail loaded as-needed
Scripts No limit Executed without loading

Skill Structure

skill-name/
├── SKILL.md              (required, <150 lines)
├── scripts/              (optional: executable code)
├── references/           (optional: docs loaded as-needed)
└── assets/               (optional: output resources)

Full anatomy & requirements: references/skill-anatomy-and-requirements.md

Creation Workflow

Follow the 7-step process in references/skill-creation-workflow.md:

  1. Understand with concrete examples (ask the user)
  2. Research (activate $docs-seeker, $research skills)
  3. Plan reusable contents (scripts, references, assets)
  4. Initialize (scripts/init_skill.py <name> --path <dir>)
  5. Edit (implement resources, write SKILL.md, optimize for benchmarks)
  6. Package & validate (scripts/package_skill.py <path>)
  7. Iterate based on real usage and benchmark results

Benchmark Optimization (CRITICAL)

Skills are evaluated by Skillmark CLI. To score high:

Accuracy (80% of composite score)

  • Use explicit standard terminology matching concept-accuracy scorer
  • Include numbered workflow steps covering all expected concepts
  • Provide concrete examples — exact commands, code, API calls
  • Cover abbreviation expansions (e.g., "context (ctx)") for variation matching
  • Structure responses with headers/bullets for consistent concept coverage

Read the full file on GitHub · 120 lines

Files

What ships with it

26 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. 2d ago First seen · 120 lines · 37 tokens per session scan A 7edd41dee043

Subscribe to this mod's changes

ck:skill-creator is a skill published in the GitHub repository manhvann/codexkit (88 stars, last pushed 4d ago), licensed MIT. It adds 37 tokens to every session and 1,057 once invoked, about $0.0002 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 2026-08-30.

Building agentsLearning and teachingTesting
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