---
id: "concept-skill-anatomy"
type: "concept"
source_timestamps: ["04:38:00", "04:45:00"]
tags: ["file-structure", "markdown"]
related: ["concept-description-routing-signal", "concept-methodology-body", "prereq-markdown-structure"]
definition: "The basic structure of a skill: a folder containing a single skill.md file, which is divided into metadata (description) and methodology."
sources: ["s43-file-format-agreement"]
sourceVaultSlug: "s43-file-format-agreement"
originDay: 43
---
# The Anatomy of a Skill

## Definition

The basic structure of a skill: a folder containing a single `skill.md` file, divided into metadata (description) and methodology.

## The Two Components

At its core, a skill is an incredibly simple primitive — just a folder containing a text file, typically named `skill.md`. This file has two required components:

### 1. Metadata (the description)

The metadata at the top, primarily the `description` field, tells the system *what the skill does*. This is the **routing signal** ([[concept-description-routing-signal]]) — the field an agent reads when deciding whether to invoke the skill.

### 2. Methodology (the body)

The `methodology` body below the metadata contains the plain-English instructions on *how* to execute the task. This is structured according to the [[framework-skill-methodology]] (the 5-Part Methodology Body — see [[concept-methodology-body]]).

## Why Simplicity Is Power

Despite this simplicity, the power of the skill lies in **how** these two sections are engineered:

- The description must be optimized for **agent routing**.
- The methodology must be optimized for **LLM reasoning and edge-case handling**.

Because a skill is just a markdown file, it can be:

- version-controlled
- shared across teams and orgs
- treated as a standard piece of organizational infrastructure

## Related

- [[prereq-markdown-structure]] — basic markdown literacy required
- [[concept-skills-vs-prompts]] — why this primitive matters more than ad-hoc prompts