Agent skill packs, skills CLIs and registries
How Agent Skills are installed, discovered and shared across Claude Code, Codex, Gemini CLI, Cursor and Copilot, and how the main installers (skills CLI, plugin marketplaces) and skill packs compare on format, harness support, licence and install command.
Comparison
| Entry | What it is | Format | Harness support | Licence | Install command |
|---|---|---|---|---|---|
| skills CLI (npx skills) | Vercel's open installer and manager (add, use, list, find, update, remove, init); its directory is skills.sh | Installs any Agent Skills folder from GitHub, GitLab, Azure DevOps, any git URL, a local path or a download URL | OpenCode, Claude Code, Codex, Cursor and 75 more per its README; target agents with -a. Symlinks one canonical copy into each agent, or copies with --copy | MIT | npx skills add <owner/repo> [--skill name] [-a claude-code] [-g] |
| Anthropic Agent Skills (anthropics/skills) | Anthropic's example and document skills (for example pdf and skill-creator) | Agent Skills, packaged as Claude Code plugins through a marketplace | Claude Code, Claude.ai (already available on paid plans) and the Claude API | Mixed, set per skill: example skills such as skill-creator are Apache-2.0; document skills such as pdf are proprietary (all rights reserved). No repo-level licence | /plugin marketplace add anthropics/skills, then /plugin install document-skills@anthropic-agent-skills |
| Vercel Agent Skills | Vercel's skills for React and Next.js best practices, web design guidelines and Vercel deploys | Agent Skills (SKILL.md plus optional scripts/ and references/) | Any agent the skills CLI supports | MIT according to the README; GitHub detects no licence file | npx skills add vercel-labs/agent-skills |
| Matt Pocock's Skills | Engineering and productivity skills (tdd, code-review and more) | Agent Skills, also shipped as plugins for several harnesses | Native plugins for Claude Code, Codex, Copilot and VS Code; Gemini CLI via gemini skills install; Cursor, OpenCode, Windsurf and others via the skills CLI | MIT | claude plugin install mattpocock-skills@claude-plugins-official, or npx skills@latest add mattpocock/skills -a <agent> |
| Superpowers | A methodology built from composable skills (brainstorming, TDD, systematic debugging) | Agent Skills distributed as a plugin | Claude Code and Codex (official marketplaces), Cursor, Antigravity, Devin CLI and others; installed separately per harness | MIT | /plugin install superpowers@claude-plugins-official (Claude Code); /add-plugin superpowers (Cursor) |
| Hugging Face Skills | Skills for AI/ML work on the Hugging Face Hub; hf-cli is the bootstrap skill | Agent Skills, with Claude, Cursor and Codex plugin manifests and a Gemini CLI extension | Claude Code, Codex, Gemini CLI, Cursor | Apache-2.0 | /plugin marketplace add huggingface/skills, then /plugin install hf-cli@huggingface/skills; more skills with hf skills add <name> |
| Emil Kowalski's Skills | Design-engineering skills focused on animation (emil-design-eng, animate, review-animations and more) | Agent Skills | Any agent the skills CLI supports | MIT (GitHub repo emilkowalski/skills) | npx skills add emilkowalski/skill |
| Google Agents CLI | A CLI plus skills for building, evaluating and deploying agents on Google Cloud | Agent Skills plus a companion CLI (agents-cli) | Installs its skills into coding agents (agents-cli setup); also available through the skills CLI | Apache-2.0 | uvx google-agents-cli setup, or npx skills add google/agents-cli |
Verdict: Write skills once in the Agent Skills format and commit them to .agents/skills/. Codex, Gemini CLI, Cursor and Copilot all read that path; Claude Code reads .claude/skills/. For a cross-harness install, use npx skills add; it symlinks one copy into each agent. Use a harness's plugin marketplace when you want automatic updates. Check licences per skill: Anthropic's document skills are not open source.
The format
The Agent Skills spec defines a skill as a folder with a SKILL.md. Its YAML front matter needs name (at most 64 characters: lowercase letters, digits and hyphens) and description (at most 1024 characters, saying what the skill does and when to use it). Optional fields are license, compatibility, metadata and the experimental allowed-tools. Scripts, references and assets can sit alongside. The spec advises keeping SKILL.md under 500 lines. Harnesses load only the name and description up front and read the body when the skill becomes relevant (progressive disclosure).
Where each harness looks
| Harness | Project skills | Personal skills | Sharing and distribution |
|---|---|---|---|
| Claude Code | .claude/skills/ (cwd and parent directories) | ~/.claude/skills/ | Plugins and marketplaces (/plugin); skills synced from claude.ai; enterprise managed settings |
| Codex | .agents/skills/ from cwd up to the repo root | $HOME/.agents/skills/; admin /etc/codex/skills | Plugins in the plugin directory shared by ChatGPT and Codex; /skills or $ to mention a skill |
| Gemini CLI | .gemini/skills/ or .agents/skills/ (the alias wins) | ~/.gemini/skills/ or ~/.agents/skills/ | Extension-bundled skills; gemini skills install <git-url>, list, uninstall; the model activates a skill with activate_skill |
| Cursor | .agents/skills/, .cursor/skills/ | ~/.agents/skills/, ~/.cursor/skills/ | Also loads .claude/skills/ and .codex/skills/ (project and home); plugin marketplace; / to invoke |
| GitHub Copilot (CLI) | .github/skills/, .claude/skills/, .agents/skills/ | ~/.copilot/skills/, ~/.agents/skills/ | gh skill in GitHub CLI to discover and install from GitHub repos; the community collection github/awesome-copilot |
So .agents/skills/ is the closest thing to a portable path: Codex, Gemini CLI, Cursor and Copilot read it. Claude Code documents only .claude/skills/, which Cursor and Copilot also read. A repo that wants to serve every harness can keep its skills in one place and symlink the other path, which is what the skills CLI does for you.
Installers and registries
- skills CLI (
npx skills) is harness-neutral. It installs from any git source, lists a repo's skills (--list), installs project-level or globally (-g), targets agents (-a), and updates or removes them.npx skills useruns a skill without installing it. Its directory, skills.sh, ranks skills by installs. - Plugin marketplaces in Claude Code, Codex, Cursor, Copilot and VS Code bundle skills with other extensions (MCP servers, hooks) and update them automatically. Matt Pocock's README warns against using both routes for the same agent: the plugin updates itself, while skills.sh copies editable files that you update by hand.
- Harness CLIs:
gemini skills install(Gemini CLI) andgh skill(GitHub CLI). - Curated lists such as awesome-claude-skills and travisvn/awesome-claude-skills help discovery but don't install anything.
Notes on the packs
- Anthropic's repo mixes licences. Read each skill's
LICENSE.txtbefore redistributing. - Several packs ship a bootstrap skill: Hugging Face's
hf-cliand Matt Pocock'ssetup-matt-pocock-skills. - Skills run with your agent's permissions. Review scripts in third-party packs as you would any dependency.
For a feature-level comparison of the harnesses themselves, see Coding agent harnesses.
Directory entries in this comparison
- Agent Skills Specification: Open format for packaging agent capabilities as folders with a SKILL.md (YAML frontmatter + instructions) plus optional scripts and resources.
- skills CLI (npx skills): Vercel's open agent skills tool: install, update and manage Agent Skills for many coding agents with `npx skills add <source>`.
- skills.sh: The open Agent Skills directory: browse skills ranked by installs and install them into your agent with one command.
- Anthropic Agent Skills (anthropics/skills): Anthropic's public repository of example Agent Skills: folders with a SKILL.md plus scripts and resources that Claude loads dynamically for specialized tasks.
- Vercel Agent Skills: Vercel's official collection of Agent Skills, including React best practices, composition patterns and web design guidelines.
- Matt Pocock's Skills: Engineering-focused Agent Skills from Matt Pocock (e.g. tdd, code-review, grill-me), among the most-installed skill packs on skills.sh.
- Superpowers: Agentic skills framework and software-development methodology for coding agents, built from composable skills such as brainstorming, TDD and systematic debugging.
- Hugging Face Skills: Agent Skills for AI/ML work on the Hugging Face Hub: dataset creation, model training, evaluation and core hf CLI operations.
- Emil Kowalski's Skills: Skills for designers and engineers from Emil Kowalski, focused on design engineering.
- Google Agents CLI: CLI and skills that turn any coding assistant into an expert at creating, evaluating and deploying AI agents on Google Cloud.
- Claude Code: Anthropic's agentic coding tool that reads your codebase, edits files, runs commands and integrates with dev tools; available in terminal, IDE, desktop and browser.
- OpenAI Codex CLI: OpenAI's lightweight open-source coding agent that runs in your terminal.
- Gemini CLI: Open-source AI agent from Google that brings Gemini models directly into your terminal.
- Cursor: AI code editor and coding agent with Agent mode, Rules, Skills, MCP servers and a CLI.
- GitHub Copilot CLI: Brings GitHub Copilot's coding agent to your terminal to read, write and run code where you work.
- OpenCode: The open-source AI coding agent, built for the terminal.
- Awesome Claude Skills (Composio): Curated GitHub list of Claude Skills, resources and tools for customizing Claude workflows.
- Awesome Claude Skills (travisvn): Curated list of Claude Skills, resources and tools for customizing Claude workflows, particularly Claude Code.
Related
- IDE and cloud coding agents compared (Comparison)
- Terminal coding agents compared (Comparison)
- Index Agentica lookup (Skill)
- Add MCP servers to Claude Code (Guide)
- OpenClaw vs Hermes Agent vs Pi: open-source agents you run yourself (Comparison)
Sources
- Agent Skills specification, accessed
- skills CLI README, accessed
- Claude Code docs, Skills, accessed
- ChatGPT and Codex docs, Build skills, accessed
- Gemini CLI docs, Skills, accessed
- Cursor docs, Agent Skills, accessed
- GitHub Docs, Agent skills, accessed
- anthropics/skills README, accessed
- anthropics/skills pdf LICENSE, accessed
- anthropics/skills skill-creator LICENSE, accessed
- vercel-labs/agent-skills README, accessed
- mattpocock/skills README, accessed
- obra/superpowers README, accessed
- huggingface/skills README, accessed
- Emil Kowalski, AI Skills for Design Engineers, accessed
- emilkowalski/skills repository, accessed
- google/agents-cli README, accessed