Claude Skills (Anthropic calls them Agent Skills) package instructions, scripts and reference files that Claude loads when a task needs them. You write a procedure once, and Claude follows it every time the task comes up, without you pasting the same guidance into each chat.
What a skill is
A skill is a folder. Inside it sits a SKILL.md file that opens with two required fields, name and description, followed by plain instructions. The folder can also hold extra reference files, templates and scripts Claude can run.
Anthropic's documentation describes three levels of loading:
- Metadata: the name and description of every installed skill load at startup, about 100 tokens per skill.
- Instructions: the body of SKILL.md loads only when your request matches the description. Anthropic puts this at under 5k tokens.
- Resources: bundled files cost nothing until Claude opens them. When Claude runs a script, only its output enters the context.
This lets you keep many skills installed without filling Claude's context. Anthropic developed the format and released it as an open standard; agentskills.io lists Cursor, Gemini CLI, GitHub Copilot and OpenAI Codex among the tools that read skills. Our manual explains how Claude Skills work and how to write one.
Where skills work
Skills run on three Anthropic surfaces, and each one handles them differently. Anthropic's platform docs say custom skills do not sync across surfaces. The one documented exception: Claude Code in a terminal, signed in with a claude.ai account (version 2.1.273 or later), downloads the skills enabled on that account. The API keeps its own copies.
| Surface | Skills from Anthropic | Your own skills | Who sees them |
|---|---|---|---|
| Claude.ai | Word, Excel, PowerPoint and PDF skills, used automatically when you create files | Upload a ZIP under Customize > Skills | You; Team and Enterprise owners can provision skills for everyone |
| Claude Code | Bundled skills such as /code-review; the document skills arrive only through claude.ai sync or a plugin | A folder in ~/.claude/skills/ or .claude/skills/ | You, the project, or anyone using a plugin |
| Claude API | pptx, xlsx, docx, pdf by skill ID | Upload through the /v1/skills endpoints | Everyone in the workspace |
Claude.ai and the API need code execution. In Claude.ai, Anthropic's help center lists skills on the Free, Pro, Max, Team and Enterprise plans, with the "Code execution and file creation" setting turned on. On the API, skills run in a sandbox with no network access and no package installs at runtime.
How to install a skill
In Claude.ai
- Open Settings > Capabilities and turn on "Code execution and file creation". On Team and Enterprise plans, an owner enables skills for the organization first.
- Go to Customize > Skills to switch individual skills on or off.
- To add your own, package the skill folder as a ZIP, click "+", then "+ Create skill", choose "Upload a skill" and select the file.
In Claude Code
Copy the skill folder into ~/.claude/skills/ for all your projects, or into .claude/skills/ inside a repository to share it with your team. Claude picks it up automatically, and you can also call it by name, for example /skill-name. To install Anthropic's example set as a plugin, run:
/plugin marketplace add anthropics/skills
/plugin install example-skills@anthropic-agent-skillsThrough the API
Pass the skill in the container parameter of a Messages API request, together with the code execution tool. Anthropic's skills use "type": "anthropic" and a skill ID such as pptx.
Claude skills on GitHub
Three kinds of repositories hold most of the skills people install:
- anthropics/skills, Anthropic's own skills repo. Many of its skills are open source under Apache 2.0. The Word, Excel, PowerPoint and PDF skills are published as source-available, not open source.
- anthropics/claude-plugins-official, the curated plugin directory for Claude Code. Its
/pluginsfolder holds plugins Anthropic builds and maintains;/external_pluginsholds third-party ones. Install any of them with/plugin install {plugin-name}@claude-plugins-official. - Community repositories, such as blader/humanizer and mattpocock/skills. Anthropic does not publish these.
A skill can tell Claude to run code and use tools, so source matters. Anthropic advises using skills you wrote or got from Anthropic, and reading every bundled file of anything else first. Look for network calls, file access or steps that do not match what the skill claims to do. A skill that fetches content from outside URLs deserves extra care, because that content can change after you install it.
Best Claude skills to start with
There is no official ranking of the best Claude skills. These are the ones our guides cover, by job. New to skills? Read the Claude Skills manual first, then try skill-creator to turn one of your own routines into a skill. For interface work, see frontend-design; for checking code before a pull request, the bundled code review skill. If you prefer to work with prompts, our Claude prompts library and Claude Code prompts work without installing anything.
Sources
- Agent Skills overview — Claude Platform Docs, accessed October 2026
- Using skills in Claude — Claude Help Center, accessed October 2026
- Extend Claude with skills — Claude Code Docs, accessed October 2026
- anthropics/skills — GitHub, accessed October 2026
- Get started with Agent Skills in the API — Claude Platform Docs, accessed October 2026
- Agent Skills overview — agentskills.io, accessed October 2026
- claude-plugins-official — GitHub, accessed October 2026