Skill authoring best practices

# Skill authoring best practices > Learn how to write effective Skills that Claude can discover and use successfully. Good Skills are concise, well-structured, and tested with real usage. This guide provides practical authoring decisions to help you write Skills that Claude can discover and use effectively. For conceptual background on how Skills work, see the [Skills overview](/en/docs/agents-and-tools/agent-skills/overview). ## Core principles ### Concise is key The [context window](https://platform.claude.com/docs/en/build-with-claude/context-windows) is a public good. Your Skill shares the context window with everything else Claude needs to know, including: * The system prompt * Conversation history * Other Skills' metadata * Your actual request Not every token in your Skill has an immediate cost. At startup, only the metadata (name and description) from all Skills is pre-loaded. Claude reads SKILL.md only when the Skill becomes relevant, and reads additional files only as