Ebook · PDF and EPUB · about 280 pages

The Claude Code & Codex Skills Guidebook

53 agent skills, each tested in both Claude Code and Codex. For every skill: who it fits, the install commands for each tool, a first run, and what to watch out for.

Buy on Leanpub — from $19Free sample (28 pages)

Suggested price $29. Every future edition free. 60-day refund on Leanpub.

Book cover: The Claude Code & Codex Skills Guidebook, 53 agent skills tested in both tools, by Jay Jung Lim

Why this book

Thousands of agent skills sit on GitHub. Most come with a terse README written for developers, and few tell you whether a skill fits your work before you install it. A skill that does not fit costs you an afternoon and a cluttered skills folder.

This guide does the sorting for you. Each skill was installed and run in both tools, and each chapter starts with a table of where it fits and where it does not.

What every skill chapter gives you

  1. Who it fits. Situations rated good fit, okay, or poor fit, with a reason for each.
  2. Install. The commands for Claude Code and for Codex.
  3. First run. What to type and what the skill does step by step.
  4. What makes it useful, and what to watch out for. Limits, risks, and what it will not do.
  5. Sources. Repository, license, and the files the chapter quotes.
A page from the book: the humanizer chapter with its At a glance table and Who it fits table
From chapter 02-02, humanizer
A page from the foundation chapter that explains agents, skills, subagents, MCP and hooks
From the foundation chapter on agents and skills

The 53 skills

Grouped by the work you do. A roadmap chapter pairs them by role: planning, design, development, marketing, operations, and research.

Part 01 Business

  • pm-skills Product planning methods
  • distilly Turn a person's approach into a skill
  • wondelai/skills Frameworks from business books
  • yc-office-hours A business mentor who asks before you build
  • research Research into a document with sources
  • flow-map Flowcharts as dated snapshots
  • meeting-agenda Agendas that force options and deadlines

Part 02 Marketing

  • marketingskills Practical marketing skills
  • humanizer Edit machine-like prose
  • claude-ads Audit ad accounts
  • blog-post A production cycle for one post
  • blog-topic-judge Score blog topics on five axes
  • technical-writer Writing steps by document type
  • card-news A card deck from one JSON file

Part 03 Data analysis

  • last30days-skill Summarize recent reactions
  • nature-skills Check figures and statistics for submission
  • notebooklm-py Control NotebookLM with commands
  • insane-search Read blocked public pages
  • apps-script-collector Daily market prices into a sheet

Part 04 Design

  • archify Validated architecture diagrams
  • diagram-design 44 diagram types in brand colors
  • huashu-design Design outputs in HTML
  • architecture-drawio-diagram Architecture diagrams with large logos
  • lecture-slide-make Editable lecture decks from one JSON file
  • lecture-slides A deck workflow for recorded lectures and seminars
  • notebooklm-slides Image decks from a spec

Part 05 Development

  • superpowers From design through merge
  • agent-skills Procedures for each dev stage
  • n8n-skills Knowledge for n8n workflows
  • n8n-route Pick the instance, enforce build rules
  • n8n-workflow-builder Workflow design and final checks
  • n8n-debugger Trace failures and prevent repeats

Part 06 Operations

  • obsidian-skills Work in an Obsidian vault
  • gmail-search Find email four ways
  • email-draft Gmail drafts with your signature
  • add-launchd-job Six steps to a launchd job
  • new-project Check names, then create a folder
  • markdown-to-pdf Markdown to PDF
  • aside-browser Entry point for Aside CLI

Part 07 Working with agents

  • i-have-adhd Action first, numbered steps
  • grilling Test plans with questions
  • plan Plan, cross-review, wait for approval
  • planning-with-files Plans that survive interruptions
  • session-wrap Commit and hand off before you stop
  • skill-creator Write and evaluate skills
  • skill-recorder Turn recorded work into a skill
  • SkillSpector Security check before install

Part 08 Vibe coding

  • gstack Development commands by role
  • taste-skill Rules against generic screens
  • ponytail Rules for writing less code
  • ui-ux-pro-max Industry-specific design rules
  • Understand-Anything A knowledge graph of your codebase
  • open-code-review Review changed code automatically

Plus foundation chapters: what agents, skills, subagents, MCP, and hooks are; how each tool finds and loads a SKILL.md; the spec differences; and how to share one skill folder between both tools.

Get all 53 — from $19 or read the free 28-page sample

Is it for you?

Good fit

  • You use Claude Code or Codex and repeat the same instructions every session.
  • You are a developer, indie hacker, or solo founder looking for skills that pay off this week.
  • You switch between both tools and want one skill folder that works in each.

Not a fit

  • You want a general prompt-writing guide.
  • You need install help for plans and billing of the two products.
  • You only use chat apps and never open a terminal.
Portrait of Jay Jung Lim

About the author

20+ organizations trained6,000+ Claude sessions1,000+ Codex sessions70 skills in daily use

Jay Jung Lim is the founder of BuildnWrite, a Seoul-based studio for AI agent coaching and corporate AI training. Since 2023 Jay has trained teams at more than 20 organizations and coauthored n8n Does It All (Hanbit Media, 2026). Jay uses 70 skills in daily work and logged more than 6,000 Claude sessions and 1,000 Codex sessions while building this book.

LinkedIn (opens in a new tab)

Questions

What formats do I get?
PDF and EPUB, about 280 pages. Read them on a laptop, tablet, or e-reader.
Do I need to know how to code?
No. You need Claude Code or Codex installed and you need to paste commands into a terminal. If you have never installed either tool, the chapter "Getting started with Claude Code and Codex" walks you through it.
Which versions does it cover?
Claude Code v2.1.273 and Codex v0.153.4, on macOS. On Windows, the same commands work in WSL2.
What about updates?
Both tools change fast, so the book is revised as skills and tools change. On Leanpub, every buyer gets each new edition free.
Can I get a refund?
Leanpub offers a 100% refund within 60 days of purchase.
Is this an official Anthropic or OpenAI book?
No. It is an independent guide by BuildnWrite. Product names belong to their owners.

Get the book

PDF and EPUB, about 280 pages. Pay what you want from $19 (suggested $29). Every future edition free.

Buy on Leanpub — from $19Read the free sample first

Not useful to you? Leanpub refunds 100% within 60 days.