Ebook, PDF and EPUB, about 280 pages

53 agent skills worth installing, already tested in Claude Code and Codex

Thousands of skills sit on GitHub. The Claude Code & Codex Skills Guidebook picks the ones worth your time, runs each in both tools, and tells you in one table whether it fits your work before you install anything.

See packages, from $29Free sample (29 pages)

The book for $29, or the book plus 20 ready-to-install skills, 6 subagents, and a six-role ops team for $59.

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

Why pay for something you could piece together for free?

You could. Most of these skills are on GitHub, and the original Korean edition of this book is free to read online. What you would be missing is the sorting.

A skill's README rarely says who it is for. Finding out means installing it, running it, and cleaning up when it does not fit. That costs an afternoon per skill and leaves your skills folder cluttered.

This book has already done that work. Every skill was installed and run in both Claude Code and Codex, and every chapter follows the same layout, so you can compare skills side by side and decide in minutes.

What every skill chapter gives you

Same five parts, same order, in all 53 chapters.

  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

Is it for you?

Good fit

  • You have bookmarked more skill repos than you have tried, and want to know which ones are worth an install.
  • 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.

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.

See packages, from $29 or read the free 29-page sample

Portrait of Jay Jung Lim

About the author

14 months using Claudeabout $1,100 (₩1.5M) paid to Claude out of pocket6,275 Claude Code sessions1,577 hours of active work1,048 Codex sessions20+ organizations trained since 2023

Usage figures from the author's Claude and Codex logs, as of October 2026.

Jay Jung Lim is the founder of BuildnWrite, and an AI agent coach based in Seoul. Since 2023 Jay has trained teams at more than 20 organizations and coauthored n8n Does It All (Hanbit Media, 2026). This book is the shortlist Jay wished existed: 70 skills in daily use, more than 6,000 Claude sessions and 1,000 Codex sessions behind it.

LinkedIn (opens in a new tab)

Questions

Isn't this information free on GitHub?
Many of the skills are, and the Korean edition of this book is free to read online. What you pay for is the sorting: 53 skills picked out of thousands, each run in both tools, each written up in the same layout so you can decide quickly. The English edition also comes as a PDF and EPUB you can keep.
Do I get updates?
Yes, for 12 months from purchase. New editions of the book and the Skill Pack are added to your Gumroad library at no cost. Both tools change fast, and both are revised as they do.
What is in the Skill Pack?
20 skills from the author's daily work, 6 subagents, and a six-role one-person operations team, cleaned of personal settings, with an installer that copies them into Claude Code and links them into Codex. Licensed for your own and your organization's internal use.
How does the setup call work?
After purchase you get a short questionnaire by email. We meet for 60 minutes on Zoom or Google Meet; I am in Seoul (UTC+9), and Seoul mornings line up with US evenings. Afterwards you receive a Claude Code Setup Blueprint (PDF).
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.
Can I get a refund?
For the book and the book + Skill Pack, email contact@buildnwrite.com within 30 days of purchase for a full refund. The setup call is fully refundable any time before the call; the Blueprint made after it is custom work and is not refundable.
Is this an official Anthropic or OpenAI book?
No. It is an independent guide by BuildnWrite. Product names belong to their owners.

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