Skills work across Claude.ai, Claude Code, and the API. Claude identifies relevant Skills and applies them automatically. They can also stack together for complex workflows.
Claude can now use Skills to improve how it performs specific tasks. Skills are folders that include instructions, scripts, and resources that Claude can load when needed.
Claude will only access a skill when it’s relevant to the task at hand. When used, skills make Claude better at specialized tasks like working with Excel or following your organization’s brand guidelines.
Skills are conceptually extremely simple: a skill is a markdown file telling the model how to do something, optionally accompanied by extra documents and pre-written scripts that the model can run to help it accomplish the tasks described by the skill.
There is nothing at all preventing them from being used with other models. You can grab a skills folder right now, point Codex CLI or Gemini CLI at it and say “read pdf/SKILL.md and then create me a PDF describing this project” and it will work, despite those tools and models having no baked in knowledge of the skills system.
Enable Skills and build your own in Settings > Capabilities > Skills.