SKILL.md Format Guide

Understand what SKILL.md is, how it differs from marketplace or install terms, and why the file format matters for cross-platform skill portability.
Mar 8, 2026

SKILL.md Format Guide

SKILL.md is the core file format behind most Agent Skills. Users searching for “skills md” or “skill md” are usually asking about the file standard, not a product brand. This page explains the format directly and then points you back to the most useful browse paths.

What belongs in SKILL.md

A strong SKILL.md usually answers four questions clearly:

  • what the skill does
  • when it should be used
  • what inputs or context it expects
  • what outputs or operating rules the agent should follow

Some repositories also include scripts, examples, or runtime-specific notes, but the core purpose of SKILL.md is still workflow definition.

Why format matters for compatibility

The file format is where portability begins. If a skill uses clear instructions and avoids unnecessary platform lock-in, it has a better chance of appearing on multiple relevant pages such as Claude Code, Codex, Cursor, or Gemini CLI.