A folder Claude reads when it needs to be precise
A Skill is a folder containing a SKILL.md (instructions + frontmatter), optional supporting files (templates, checklists, schemas), and optional scripts. The host AI loads it dynamically when relevant — explicitly via /skill-name, automatically based on the description, or always-on per Skill config. Same shape across every compliant tool.
Why this exists: prompt drift. The same task asked five different ways gets five different outputs. Skills move the canonical instructions out of conversation memory and into a versioned file. The agent reads the same instructions every time; the output stays consistent across users, sessions, machines.
Skills follow the open Agent Skills standard. A well-written Skill works in Claude Code, Cowork, and third-party tools that implement the spec — write once, deploy across the agent landscape. That portability is the whole reason the standard exists.