Agent Skills (Addy Osmani) 🧩 Skill Open source
25 lifecycle skills and commands that make agents spec, test, review and ship with discipline
- GitHub stars
- 100k
- Stars this week
- +1.4k
- Forks
- 11k
- Licence
- MIT
- Last push
- 2026-10-02
- Maintainer
- addyosmani
npx skills add addyosmani/agent-skillsThird-party agent skills run with your permissions. Read the source before installing, and prefer pinned versions.
Works with
Built on the open Agent Skills standard, so it works in every app that supports Agent Skills.
DSCODEAbout Agent Skills (Addy Osmani)
What it does
Agent Skills, created by Addy Osmani with two collaborators, is a pack of engineering workflows for AI coding agents. It aims to stop agents from taking shortcuts such as skipping the spec, the tests or the review. The skills follow the development lifecycle in six phases: define, plan, build, verify, review and ship. Nine slash commands (/spec, /plan, /build, /test, /review, /ship and others) act as entry points, and skills also switch on automatically when the task matches.
What is inside
- 25 skills: 24 lifecycle skills plus a meta-skill that routes work to the right one. Examples include spec-driven development, planning and task breakdown, test-driven development, incremental implementation, debugging, code review, security hardening, performance, CI/CD, deprecation and migration, and observability.
- 4 agent personas: code reviewer, test engineer, security auditor and web performance auditor.
- 7 reference checklists: definition of done, testing patterns, security, performance, accessibility, observability and orchestration.
Each skill has steps, red flags, a table of excuses agents use to skip steps with rebuttals, and evidence the agent must show before calling the work done. Many practices come from Google's published engineering guidance.
Works with
The README documents Claude Code (plugin marketplace), Codex (native plugin), Gemini CLI, Antigravity CLI, Cursor, OpenCode, GitHub Copilot, Kiro, Windsurf and Command Code. Any other agent that reads SKILL.md files can use the skills/ folder.
How to install
npx skills add addyosmani/agent-skillsIn Claude Code:
/plugin marketplace add addyosmani/agent-skills
/plugin install agent-skills@addy-agent-skillsMaintenance and safety
MIT licensed and very actively maintained, with routing evals and CI in the repository. The skills are mostly Markdown. The Claude Code plugin adds lifecycle hooks, so review them before you enable it. Installing a single skill with npx leaves out the shared references/ folder.
Who should use it
Developers and teams who want an agent to work like a careful senior engineer, especially on production code where specs, tests and reviews matter more than raw speed.
Pros
- Covers the whole lifecycle with verification gates and anti-rationalization tables
- Native install paths documented for many agents
- Includes reviewer personas and reusable checklists
Cons
- Opinionated, process-heavy workflows can slow quick prototypes
- Single-skill npx installs omit the shared references folder
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