What Are Claude Code Skills? How Agent Skills Work (2026)

A Claude Code skill is a folder of instructions, example scripts and reference context that gets loaded into the agent so it performs a specific task the way an expert would, instead of guessing from a blank prompt each time. The catalog behind this site tracks 65,854 skills alone (skills.sh registry, June 2026); this guide explains what they are and how to pick between them.

Key takeaways

• A skill is a package of instructions, scripts and reference material - SKILL.md plus supporting files - that Claude Code loads for a specific task on install.
• The skills.sh registry tracks 65,854 skills, 7,867 MCP servers, 2,385 plugins and 9,196 marketplaces - 85,302 listings in total, with 120,148,840 combined installs (skills.sh registry, June 2026).
• Skills differ from MCP servers: a skill teaches the agent how to do something; an MCP server gives it a live connection to an external system. See What is MCP for that distinction.
• The catalog's largest single subphase is build/agent-tooling at 37,101 listings (skills.sh registry) - the majority of skills exist to make Claude Code better at building software, not at using it for other tasks.
• Skills install with a single command (claude skills install <name>) and stack - most real workflows (like UI design) combine 3-5 skills, not one.

What exactly is inside a Claude Code skill?

A skill is a directory built around a SKILL.md file that describes when Claude Code should use it and what it should do, plus any supporting scripts, templates or reference documents the instructions point to. When installed, Claude Code reads this content into its context for the relevant task, so the agent follows a documented, repeatable procedure instead of improvising one from scratch every session.

How big is the Claude Code skills ecosystem?

Large and still growing: the skills.sh registry - the upstream catalog this site indexes - tracks 65,854 skills, 7,867 MCP servers, 2,385 plugins and 9,196 marketplaces, for 85,302 listings and 120,148,840 combined installs (skills.sh registry, June 2026). The single largest segment is build/agent-tooling at 37,101 listings, meaning the majority of the ecosystem is builders making Claude Code better at writing and shipping code.

What is the best way to find a Claude Code skill?

Search Skillselion's catalog by task rather than by name - the same problem (design a UI, build an MCP server, audit accessibility) is often solved by multiple competing skills with very different install counts. For frontend and design work specifically, start with How to Design a UI with Claude Code, which walks through a real four-skill stack rather than a single pick.

How do Claude Code skills work?

Under the hood the flow has three steps. First, install drops the skill's folder into your skills directory, and the SKILL.md frontmatter (name + description) is registered with the agent. Second, triggering: Claude Code reads the description to decide when the skill applies - when your request matches, it loads the full SKILL.md into context. Third, execution: the agent follows the skill's instructions and can run any bundled scripts or read the reference files the instructions point to. This is progressive disclosure: only the short description occupies context permanently, and the full playbook loads on demand, which is why installing many skills stays cheap until one is actually used.

Are Claude Code skills the same as agent skills?

Yes - "agent skills" is the vendor-neutral umbrella term. The same SKILL.md format works across agents (Claude Code, Codex, Cursor and others read the same packages), which is why publishers like vercel-labs/agent-skills use the broader name. "Claude Code skills" refers to that format as used by Anthropic's Claude Code specifically; every skill in this catalog is an agent skill.

How is a skill different from a plugin or a marketplace?

The catalog tracks these as three distinct listing types for a reason: a skill is a single packaged workflow; a plugin (2,385 in the catalog) typically bundles multiple skills, commands or hooks together as one installable unit; a marketplace (9,196 in the catalog) is a curated or discoverable collection that indexes many skills or plugins in one place rather than being installable itself. Installing a plugin often pulls in several skills at once - check what a plugin bundles before assuming it replaces a specific skill you need.

How is a skill different from an MCP server?

A skill changes what Claude Code knows how to do; an MCP server changes what it can connect to. mcp-builder (82,841 installs, 147,832 GitHub stars - skills.sh registry) is itself a skill, built by anthropics - one that teaches Claude Code how to construct a new MCP server. The two layers compose: a design-workflow skill can call an existing MCP server (see Figma MCP + Claude Code) to pull in live external data mid-task. Full explanation in What is MCP (Model Context Protocol)?

A complete starter stack

• One core skill for your primary workflow (design, testing, security review, etc.)
• A find-skills-style meta-skill by agentspace-so (197,572 installs, skills.sh registry) to search the catalog from inside Claude Code itself
• An MCP server only once you need a live external connection, not by default
• A plugin only once you've confirmed exactly which skills it bundles

Common pitfalls

• Installing a skill by star count alone - a niche, purpose-built skill with modest installs (like UX research skills) can outperform a popular general one for a specific task.
• Confusing a plugin with a skill - check what it bundles before assuming it's a single-purpose install.
• Assuming a skill and an MCP server solve the same problem - they operate at different layers and usually need both.

Browse the full catalog at skillselion.com/browse, or start with Best MCP Server Skills for Claude Code and How to Design a UI with Claude Code.

Common questions