Claude Skills 101

Rick Whalley

Manchester AI Huddle · April 2026

Skills are the cheapest piece of harness investment.

And the one most people still haven't touched.

What is a skill?

  • A markdown file.
  • Frontmatter says when it fires.
  • Body says what to do when it does.

That's it. No runtime. No SDK. No compile step.

Two things separate good skills from bad

  1. Description is a classifier, not documentation.
    Lead with the trigger phrases. Write for the model, not the reader.
  2. Body is a runbook, not an explanation.
    Imperative. Numbered. Concrete commands. Explicit "do not" clauses.

Rules of thumb

  • One skill, one job.
  • Keep SKILL.md under ~500 lines.
  • Progressive disclosure — references in sibling files, loaded on demand.
  • Templates go in files, not in prose.
  • Lead the description with explicit trigger phrases.
  • Two smells: never fires → fix the description. Fires but ignored → shorten and make it concrete.

Let's build one →

Live demo

Where skills live

LocationScopeUse for
~/.claude/skills/ Personal Your habits — commits, debugging, shortcuts
.claude/skills/ Project (in git) Team conventions — review, deploy, glossary
Plugin-provided Installed packs Third-party skill collections

The project tier is where the leverage is. Checked in, reviewed, inherited by everyone — including every future session.

The investment that compounds

  • Plain markdown. No runtime, no lock-in.
  • Survives harness changes. Survives model changes.
  • Institutional memory as a file tree.

The most portable piece of harness investment you can make.

Start with one.

Pick the most boring, repetitive thing you did this week.

Write a skill for it by Friday.

Longer version: fourohfour.dev/insights/claude-skills-101