Install and use skills in Claude Code, the Claude apps and the API

A skill is just a folder, so installing one mostly means putting that folder where your agent looks for it. Where that is depends on how you use the agent: in a terminal with Claude Code, in the Claude web and desktop apps, or in your own software through the API and Agent SDK. This chapter walks through each, then shows how to check that a skill is actually being used. Product menus and options change over time, so treat the specifics here as a starting point and check the current documentation if something looks different.

Before you install anything

• Read the skill’s SKILL.md and look at any scripts. It takes a couple of minutes and Chapter 6 explains what to look for.
• Check the licence, especially if you plan to use the skill at work or redistribute it.
• Make sure the folder you install contains SKILL.md at its top level, not inside an extra nested folder.

Claude Code

Claude Code discovers skills from folders on disk. There are two main places, and the difference is who the skill is for.

Skills can also arrive through plugins, which bundle one or more skills with other components. If your team uses a plugin marketplace, installing the plugin installs its skills too. Start a new session after adding a skill so the agent picks up the updated list.

Using a skill in Claude Code

You don’t need a special command. Ask for the task in ordinary words and the agent matches your request against skill descriptions. If you want to be sure, mention the job the way the description phrases it, or name the skill directly: “Use the release-notes skill to write notes for this sprint.” You can also ask the agent which skills it has available; it can see their names and descriptions.

The Claude apps (web and desktop)

In the Claude apps, skills are managed in settings rather than on disk. At the time of writing you’ll find them under Settings → Capabilities → Skills, where you can turn on built-in skills and upload your own. Custom skills are uploaded as a ZIP file of the skill folder. Depending on your plan and your organisation’s settings, skills may need to be enabled by an admin first, and code execution may need to be switched on for skills that run scripts.

1. Zip the skill folder so that the folder itself, with SKILL.md inside it, is in the archive.
2. Open Settings → Capabilities → Skills and upload the ZIP.
3. Make sure the skill is toggled on.
4. Start a new conversation and ask for the task the skill covers.

The API and the Agent SDK

If you’re building your own application, skills can be used programmatically as well. The details are product-specific and evolve, so the official documentation is the place to check exact parameters, but the broad shape is consistent:

• Through the API, skills run alongside the code execution tool, because their scripts and files need an environment to live in. You upload or reference a skill, and the model loads it with the same progressive disclosure as elsewhere.
• The Agent SDK, which provides the same agent loop that powers Claude Code as a library, can discover skills from the same kinds of folders on disk, so a skill you wrote for Claude Code can generally be reused in an SDK-based agent.
• In both cases the model sees descriptions first and loads the rest when relevant, so the writing advice in this course applies unchanged.

Other agents

Several other coding agents and tools now read SKILL.md folders too, each from its own location. Command-line installers exist that can copy a skill into the right place for whichever agent you use. The skill itself doesn’t need to change; only where you put it.

skillsOpen sourceA command-line installer for the open agent skills ecosystem.★ 37.7k · MITCClaude skill packaging guidePromptHow to package a skill folder correctly for upload.In a packUsing Agent SkillsAgent skillA skill that teaches an agent to find and use its skills.Agent skill · MIT

Is the skill working?

1. Ask the agent which skills it can see. If yours isn’t listed, check the folder location and that SKILL.md has valid frontmatter.
2. Ask for the task using words close to the description. If the skill loads now but not with your usual phrasing, the description needs work (see Chapter 9).
3. Watch the agent’s steps. Most interfaces show when a skill or file is read.
4. Compare the output with the instructions. If steps are skipped, the body may be too long or ambiguous.

Key takeaways

• Claude Code: personal skills in ~/.claude/skills/, project skills in .claude/skills/.
• Claude apps: upload a ZIP under Settings → Capabilities → Skills and switch it on.
• API and Agent SDK: the same folders work; check the documentation for current specifics.
• You trigger skills by asking for the task, not by remembering a command.