Claude Code Skills: What They Are and How I Use Them Daily

TL;DR

I'm Jim Liu, a developer in Sydney running 9 websites. I've used Claude Code Skills daily for 3+ months.
Claude Code Skills are reusable instruction playbooks — save a workflow once, invoke it with a slash command from any project
They live in ~/.claude/skills/ as Markdown files, not code packages
Different from MCP tools: Skills define how to do things; MCP tools add what Claude can access
The ones I reach for most: obra/superpowers (code review), OpenSpec (API docs), and a custom keyword-research skill I built for this site
Setup is roughly 10 minutes per skill. If you repeat the same Claude Code tasks regularly, they pay back fast

Who I Am and Why I'm Writing This

I'm Jim Liu, an independent developer based in Sydney. I run openaitoolshub.org — this site — plus 8 other web projects including a Hong Kong finance tracker, an AI plant identification app, and a few Roblox game guides.

I've used Claude Code since early 2026 and now spend 4–6 hours a day in it. Over three months I've installed around 30–40 Skills, built 4 of my own, and watched the ecosystem grow from scattered GitHub experiments to a proper marketplace with thousands of community-contributed workflows.

My take on most Skills content: it's either official documentation or a generic two-paragraph summary that clearly wasn't written by someone who ran the thing. This one is based on what I actually use every week.

What a Claude Code Skill Actually Is

A Claude Code Skill is a Markdown file with instructions Claude follows when you invoke it. Nothing more complicated than that.

Here's a stripped-down example:

---
name: check-security
description: Audit a file for common security vulnerabilities
---

Review the file at $1 for:
1. SQL injection and input validation gaps
2. Authentication logic and authorization checks  
3. Hardcoded secrets or API keys

Output a table: Issue | Severity | Line | Fix suggestion

Save that to ~/.claude/skills/check-security/SKILL.md. Then type /check-security src/api/auth.ts in any Claude Code session. Claude reads the skill instructions, applies them to your file, and returns structured output.

No build step. No package install. Just a Markdown file Claude reads directly.

The format is simple enough that you can write a basic skill in 15 minutes, but the good ones — the ones that handle edge cases and give consistent output — take iteration to get right.

Skills vs MCP Tools — The Confusion That Keeps Coming Up

These two concepts get conflated in almost every blog post about Claude Code. Quick breakdown:

MCP tools extend what Claude Code can access. Web search. Database reads. External API calls. They're capabilities — plugins that add new types of actions Claude can take.

Claude Code Skills define how Claude handles specific tasks you've already defined. They're workflows you've written out and saved for reuse.

You use both together regularly. An MCP tool might give Claude access to a search API. A Skill tells Claude exactly how to structure queries, what fields to extract, and how to format the output — so you don't re-explain that process every session.

For a detailed breakdown of where each fits in actual development work, I covered it in Claude Code Skills vs Plugins. The short version: if you're evaluating Claude Code Skills for your workflow, MCP tools solve a different problem and aren't a replacement.

How to Install a Claude Code Skill

# Clone a GitHub-hosted skill into the skills directory
git clone https://github.com/obra/superpowers ~/.claude/skills/superpowers

# Or use the official CLI install (for listed skills)
claude skills install <skill-name>

# Verify on next session start
claude --list-skills

Most well-maintained skills have a README that tells you if there's a config file or environment variable required. Read it before running anything — some skills fail silently if setup is incomplete, and you won't know why.

The Claude Code Skills I Actually Use

I've rotated through a lot of these over three months. Here's what stayed in my regular rotation.

obra/superpowers is the one I reach for most often. It does code review across an entire codebase, not just a single file. It catches patterns that file-by-file review misses — auth logic that doesn't match across endpoints, error handling that's inconsistent between modules, test coverage gaps in specific paths. I run it before any significant PR on my sites. On a medium-sized codebase, it takes 3–5 minutes and consistently surfaces things I'd missed.

OpenSpec generates structured API specifications from code or natural language. I've run it on three of my site APIs. It's not producing production-ready specs without review, but it handles the initial drafting — I'd estimate 60–70% of the spec work done before I touch it. I wrote a full review of OpenSpec here that goes into what the output actually looks like and where it needs manual work.

My own blogtool-newword-hunter is a custom skill I built to handle keyword research across my 9 sites. It runs SEMrush volume checks, SERP saturation analysis, and a dedup check against articles I've already written — in a single command. This article was partly identified using it: "claude code skills" came up as a priority target with 1,900 monthly US searches and KD 32%.

The Claude Code workflow article shows how Claude Code Skills fit into a real development day if you want more context on the actual workflow.

There's also a list of the best claude code skills currently recommended by the community at best-claude-code-skills-2026 — useful if you want to see what other developers are installing.

Where to Find Claude Code Skills in 2026

claude.com/skills — the official directory. Skills here have been reviewed and are more reliably maintained than random GitHub repos.
GitHub — search claude code skills or awesome-claude-skills. Wider selection, more experimental. Check last commit dates before installing.
Claude Skills Marketplace — the community-maintained directory. As of yesterday, it's listing 4,000+ skills across categories the official directory doesn't cover yet. I wrote a comparison of the top Claude Code Skills sources here.
r/ClaudeAI — developers sharing skills they built for specific workflows. Often rough, but covers real use cases you won't find in any directory.

Four Mistakes I Made With Skills

Worth knowing before you start:

Installing too many at once. I jumped to 15 skills in my first week. Session startup got slow, and I kept running skills I barely understood. Five or six that you actually know is worth more than twenty you've barely opened.

Skipping the parameters. Most skills accept parameters that significantly change their behavior. I used obra/superpowers at defaults for two weeks before noticing the --scope security flag that focuses the review on auth and injection. My reviews got noticeably better after that.

Trusting abandoned repos. Some Skills on GitHub haven't been updated since Claude Code 0.9. They technically run but miss features added since. Check the repo's last commit before installing anything you plan to rely on.

Assuming install means working. Skills fail silently. If you invoke a skill and the output looks wrong or incomplete, open ~/.claude/skills/{name}/SKILL.md and read it. Often there's a required parameter or environment variable I'd missed.

Where Skills Fall Short

Skills are instruction files, not code. They don't have state, they can't catch errors programmatically, and their reliability depends on Claude following instructions consistently — which it doesn't always do.

Complex multi-step workflows can drift mid-session. Claude follows the skill correctly for three steps and then improvises on the fourth. For anything production-critical, I treat skill output as a first pass and review manually.

For repetitive tasks with lower stakes — drafting docs, summarizing code, generating boilerplate, structuring research — Skills are consistently useful. For tasks touching live data or requiring exact output format, verify before using.

FAQ

What's the difference between Claude Code Skills and the Claude AI Skills platform? "Claude Skills" is used for two different things. Claude Code Skills are local Markdown files in ~/.claude/skills/ that run in Claude Code CLI sessions. Anthropic's broader Claude AI Skills platform is a separate integration framework for building external tools. Different systems, different setup.

Can I write a Claude Code Skill without coding experience? Yes. They're Markdown files. If you can write clear step-by-step instructions, you can write a skill. The hard part is being precise — vague instructions produce vague output.

Do Skills count against Claude Code's context window? Yes. The skill file loads at session start. Complex skills that are several thousand tokens can slow startup and crowd out your actual codebase context. Keep skill files under ~2,000 tokens where possible.

Are there Skills for non-developer tasks? Growing category. I've seen skills for writing workflows, market research, data formatting, and content planning. Developer-focused skills are more mature but non-dev use cases are expanding.

Where does the skill directory live on Windows? C:\Users\{username}\.claude\skills\ — same structure, different path separator. The Claude Code CLI handles path differences automatically.