Claude skills, explained with one complete example

What goes in a skill folder

Anthropic's help article writes the file name as skill.md and its docs write SKILL.md. I use SKILL.md, the spelling in the docs.

• SKILL.md. Required. It opens with two fields: name, up to 64 characters, and description, up to 200 characters (how to create custom skills). The steps come after, in plain language.
• Reference files. Optional. Longer material such as your list of clients and their preferred tone. Point to it from SKILL.md, and Claude opens it only when the steps need it.
• Scripts. Optional, for work like cleaning a spreadsheet. The skills on this page do not need one.

A complete example: the morning brief skill

Make a folder called morning-brief. Inside it, save a file named SKILL.md with exactly the text below. The folder name has to match the skill's name, so keep them the same (how to create custom skills). Change the rules to your own.

---
name: morning-brief
description: Use when the user asks for a morning brief, what is on their plate, or what needs them today. Reads Gmail and Google Calendar and returns three short lists.
---

# Morning brief

## Steps
1. Read today's Google Calendar events. For each meeting, note who it is with
   and find the last email thread with that person.
2. Search Gmail for threads from the last 3 days where someone asked the user
   a question and the user has not replied.
3. Search Gmail for messages that ask to meet. Note who asked and any times
   they proposed.
4. Return three lists, in this order: Replies owed (oldest first),
   Meeting requests, Today's meetings with one line of context each.

## Rules
- Do not draft or send anything in this skill.
- One line per item. Use first names.
- If a list is empty, write "none".

## Example output
Replies owed: Client A, question on the fee schedule, 3 days.
Meeting requests: Client B asked for next Tuesday or Wednesday morning.
Today: 10:00 Client C. Last email was about the valuation draft.

Four more worth building, with their descriptions

Each line below is the exact description I would give the skill, under the 200-character limit. The description decides when Claude picks the skill up, so it is worth getting right before writing any steps.

The examples behind the voice skill are covered in an AI email assistant that writes like you.

• Call follow-up. Use after a client call when the user shares notes or a transcript. Writes the recap email, next steps with an owner each, and a two-line CRM note.
• Reply in my voice. Use whenever the user asks for an email reply or draft. Applies their tone, length, greetings, sign-offs and never-say list, using their real sent emails as examples.
• Client prep. Use before a client meeting when the user names the client. Pulls recent threads, past notes and open items into a one-page prep sheet.
• Friday review. Use when the user asks for a weekly review or what slipped. Lists replies owed, promises not kept, and conversations that went quiet in the last 7 days.

Upload and test

• Turn on code execution. Free, Pro and Max: Settings > Capabilities. Team: skills are on by default, and an Owner confirms code execution and file creation is on under Organization settings > Plugins & skills. Enterprise: an Owner turns both on in organization settings. Anthropic's help center calls the place Plugins & skills, its docs call it Capabilities (use skills in Claude).
• Zip the folder. The ZIP must have the skill folder at its root, with SKILL.md inside it.
• Upload it. Customize > Skills, the + button, Create skill, then Upload a skill. Turn it on in the list.
• Test it. Try several requests that should trigger it, and check Claude's thinking to confirm it loaded the skill. If it did not, rewrite the description first.

What this skill won't do

It only works with Gmail and Google Calendar connected. Without them it has nothing to read.

It runs when you ask. Type morning brief, or ask what needs you today, and Claude loads it. It does not appear on its own each morning.

Anthropic does not review skills that you upload or that someone shares with you, and a skill's instructions run as part of your conversation, with whatever connectors you have on (Claude docs). Read SKILL.md and any scripts in a shared skill before you turn it on.

In my workshops I build one or two skills like this on the client's own account, then hand them over. Start with this one, then build the call follow-up next.

Questions