Skills: teach your agent a job once
If MCP gives an agent hands, skills give it training.
A skill captures how a job is done once, so you stop re-explaining your process in every conversation.
What a skill is
A skill is a folder with a SKILL.md file.
episode-packager/
├── SKILL.md required: name, description, instructions
├── references/
│ └── voice.md how the show sounds
├── assets/
│ └── description-template.md
└── scripts/
└── chapters.py optional helper codeThe file starts with a name and a description, followed by plain-language instructions. The folder can also hold scripts, reference documents, and templates the agent uses while it works.
Why it stays fast
Agents load skills through progressive disclosure.
At startup they read only each skill's name and description. When a task matches, they read the full instructions. Scripts and references load only if the instructions call for them. You can keep a large library on hand without crowding the agent's working memory.
Write once, use everywhere
Anthropic developed the format and released it as an open standard, published at agentskills.io.
A growing list of agents and coding tools reads the same SKILL.md, so a skill you write today is not locked to one product.
Skills and MCP together
| MCP server | Skill | |
|---|---|---|
| Gives the agent | Access to a system | Knowledge of a process |
| Example | Read your Google Drive | Turn a transcript into a publish-ready package |
| Lives as | A running program or remote service | A folder of text and optional scripts |
| Best for | Data and actions | Repeatable workflows and standards |
A real example
YouTube's requirements for chapters are written into step 2, so the agent never ships chapters that fail to appear.
---
name: episode-packager
description: Turns a video transcript into YouTube chapters, three
title options, and a description in The Open Experience voice.
Use when a transcript or rough-cut notes are provided.
---
# Episode packager
1. Read the full transcript. List the major beats with timestamps.
2. Write chapters. The first chapter starts at 00:00. Use at least
three chapters, each 10 seconds or longer, with plain names.
3. Write three title options under 60 characters: one led by
curiosity, one by the outcome, one direct.
4. Write the description using references/voice.md. Open with the
value of the episode in two sentences. No hype words.
5. Return everything in one block, ready to paste.Where to find more
Start with the example skills in Anthropic's public skills repository and the specification at agentskills.io.
Find the instruction you have typed into an AI more than three times. Turn it into a SKILL.md with a clear description of when to use it. That is your first skill.
The skills that will matter most, though, are the ones that encode your own process.
Resources
Every link this breakdown leans on, in one place.