Claude
Skills
What skills are and how I use them
An onboarding
guide for Claude.
Teach Claude your way once, like a new hire, and it just knows it after. That's a skill.
Prompt vs skill
- Lives in one chat
- Starts from zero every time
- You re-explain yourself
- Instructions the model follows
- Output varies each time
- Carries forward
- Teach it once
- There in every chat after
- Can bundle real code
- Runs the exact same way
- Precise part never drifts
What's inside a skill
A skill is just a folder Claude can open. It bundles everything needed to do one kind of job well: the know-how, the tools, and any reference material, in one place.
The instructions SKILL.md
A written guide telling Claude how to do the task the right way: the rules, the steps, the dos and don'ts.
The tools scripts
Small ready-made programs the skill can run to get work done, like a calculator built for the job.
Reference material resources
Extra files the skill leans on: templates, examples, or rulebooks it checks its work against.
How Claude loads a skill
It doesn't read everything at once. Each layer loads only when the task needs it, which is why a skill can hold huge reference files without slowing anything down.
Skill names & descriptions
One line per skill in your library, always in memory, very small.
The full SKILL.md
Trigger, rules, output format, dos and don'ts. Loads when your prompt matches. Typically a few KB.
Reference files & scripts
Recipes, column dictionaries, code. Can be large, only loads when the task actually needs it.
How Claude works with a spreadsheet
A spreadsheet arrives as a sealed box of data. Claude can't read it by eye, so the skill opens it, does the math, checks the work, and hands back a clean result.
You upload a file
The spreadsheet lands on a temporary computer as a sealed box of packed bytes, not readable text.
→Claude picks the skill
Seeing a spreadsheet, Claude opens the matching instructions and pulls in the right tools.
→A hidden engine runs
A small script starts a spreadsheet engine behind the scenes to work out every calculation.
→Every cell is checked
It scans the whole file for errors and reports exactly where any are, so they get fixed.
→You get a clean result
A short report confirms zero errors, and the finished spreadsheet is handed back.
The skill that
writes like you
Without context, you're just editing forever.
My writing rules
No AI tells
Em dashes, and the other giveaways.
No empty openers or closings
"I hope this finds you well."
Direct, a little punchy
The tone I actually write in.
The skill that
reads your data
Plain English in. Your definitions applied. Structured answer out.
The skill that
makes these decks
The very skill behind this presentation. Pick a look, it lays out the slides and renders them.