15 Essential Codex Skills for AI Agents: Installation Guide & Workflow Boost

The article introduces skills as plugins for AI agents — each skill is a folder containing a SKILL.md file (name, purpose, execution flow) plus optional scripts and reference files. Codex preloads skill names and descriptions into the system prompt and selects them autonomously at runtime.

Skill Installation Paths

Skills can be installed globally at ~/.codex/skills/ or per-project at .codex/skills/ or .agents/skills/. After installation, asking "What skills do you have?" confirms recognition. The official catalog lives at openai/skills: five system skills install automatically with Codex, and 39 curated skills are installable via $skill-installer. Each skill consumes context window; too many skills degrade selection accuracy.

Three Built-in Meta-Skills (1–3)

skill-creator ⭐⭐⭐ — generates new skill scaffolding; essential for creating custom skills.

skill-installer ⭐⭐⭐ — lists and installs skills from the curated catalog or local paths. Usage: $skill-installer <skill-name>.

plugin-creator ⭐ — packages a skill as a shareable plugin for team distribution.

All three reside in openai/skills/.system and install automatically. OpenAI's approach: provide production tools before a marketplace.

Development Workflow Skills (4–11)

Selection criterion: high-frequency use, measurable reliability gain over raw AI.

create-plan ⭐⭐⭐ — forces Codex to emit an implementation plan before writing code. Source: github.com/composio-community/awesome-codex-skills (create-plan subdirectory).

grill-me ⭐⭐⭐ — reverses the interaction: AI asks clarifying questions until every branch of the requirement is explicit. Source: github.com/mattpocock/skills (240k stars).

gh-fix-ci ⭐⭐⭐ — reads failing GitHub Actions logs, diagnoses root cause, and applies fixes. Install: $skill-installer gh-fix-ci. Saves ~30 minutes per week per the author.

gh-address-comments ⭐⭐ — batches PR review comments: auto-fixes actionable ones, summarizes discussion items. Install: $skill-installer gh-address-comments.

tdd ⭐⭐ — enforces red-green-refactor loop: write failing test, make it pass, refactor. Source: same as grill-me.

diagnosing-bugs ⭐⭐⭐ — imposes disciplined debugging: systematic evidence gathering before any code change. Complements tdd (prevents bugs vs. fixes bugs). Source: same as grill-me.

stop-slop ⭐⭐⭐ — strips AI-typical phrasing ("delve", "leverage", "notably") from READMEs, commit messages, docs. Source: github.com/hardikpandya/stop-slop (16.6k stars).

sentry ⭐⭐ — read-only Sentry CLI queries; summarizes production errors in plain language. Install: $skill-installer sentry.

Hardcore Supplements (12–13)

book-to-skill ⭐⭐ — ingests a PDF (your own copy) and emits a structured, on-demand-loadable skill: core mental models, per-chapter files, cheat sheet. Official benchmark: token cost 1/24 to 1/51 of stuffing the whole PDF. Source: github.com/virgiliojr94/book-to-skill (27.2k stars). Install: npx skills add virgiliojr94/book-to-skill.

playwright ⭐⭐⭐ — drives a real browser from the terminal: form filling, screenshots, data extraction, post-deploy verification, competitor scraping. Install: $skill-installer playwright. Variant playwright-interactive persists browser session for UI debugging. Community fork github.com/lackeyjb/playwright-skill (3.1k stars) adds responsive checks and login flows.

Final Two (14–15)

cangjie-skill ⭐⭐⭐ — meta-skill: feeds a book, long video, or podcast transcript; pipelines methodology into atomic capability cards compiled as installable skill packages. Distinct from book-to-skill: book-to-skill enables query-time lookup; cangjie-skill distills actionable frameworks for Codex to execute. Source: github.com/kangarooking/cangjie-skill (9.2k stars, Chinese author).

last30days ⭐⭐⭐ — non-coding research skill: given a topic or person, parallel-searches Reddit, X, YouTube, Hacker News, Polymarket; ranks by genuine engagement and financial stakes; outputs cited brief. Author's tagline: "Google aggregates editors; last30days searches people." Source: github.com/mvanhorn/last30days-skill (60.3k stars). Install: npx skills add mvanhorn/last30days-skill -g.

Portability Across AI Tools

SKILL.md

is a shared standard recognized by Codex, Claude Code, WorkBuddy, and Cursor. Practical portability: copy the same skill folder to ~/.claude/skills/ and ~/.codex/skills/ (or symlink). Skills authored in one tool work zero-cost in another. The author's thesis: tools will rotate, but a personal skill library persists.

Recommended Starter Pack

Run the three built-ins first; then pick 3–4 workflow skills (author favors create-plan and stop-slop); gh-fix-ci, gh-address-comments, sentry form a release-chain trio; add hardcore supplements per need; always include last30days.