agent-skills

# Agent Skills

**Production-grade engineering skills for AI coding agents.**

Skills encode the workflows, quality gates, and best practices that senior engineers use when building software. These ones are packaged so AI agents follow them consistently across every phase of development.

![Addy's Agent Skills](https://addyosmani.com/assets/images/addys-agent-skills.jpg)

```
  DEFINE          PLAN           BUILD          VERIFY         REVIEW          SHIP
 ┌──────┐      ┌──────┐      ┌──────┐      ┌──────┐      ┌──────┐      ┌──────┐
 │ Idea │ ───▶ │ Spec │ ───▶ │ Code │ ───▶ │ Test │ ───▶ │  QA  │ ───▶ │  Go  │
 │Refine│      │  PRD │      │ Impl │      │Debug │      │ Gate │      │ Live │
 └──────┘      └──────┘      └──────┘      └──────┘      └──────┘      └──────┘
  /spec          /plan          /build        /test         /review       /ship
```

---

## Commands

7 slash commands that map to the development lifecycle. Each one activates the right skills automatically.

| What you're doing | Command | Key principle |
|-------------------|---------|---------------|
| Define what to build | `/spec` | Spec before code |
| Plan how to build it | `/plan` | Small, atomic tasks |
| Build incrementally | `/build` | One slice at a time |
| Prove it works | `/test` | Tests are proof |
| Review before merge | `/review` | Improve code health |
| Simplify the code | `/code-simplify` | Clarity over cleverness |
| Ship to production | `/ship` | Faster is safer |

Want fewer manual steps once the spec exists? **`/build auto`** generates the plan and implements every task in a single approved pass — you approve the plan once, then it runs autonomously. It removes the human stepping *between* tasks, not the verification: every task is still test-driven and committed individually, and it pauses on failures or risky steps.

Skills also activate automatically based on what you're doing — designing an API triggers `api-and-interface-design`, building UI triggers `frontend-ui-engineering`, and so on.

---

## Quick Start

<details>
<summary><b>Claude Code (recommended)</b></summary>

**Marketplace install:**

```
/plugin marketplace add addyosmani/agent-skills
/plugin install agent-skills@addy-agent-skills
```

> **SSH errors?** The marketplace clones repos via SSH. If you don't have SSH keys set up on GitHub, either [add your SSH key](https://docs.github.com/en/authentication/connecting-to-github-with-ssh/adding-a-new-ssh-key-to-your-github-account) or use the full HTTPS URL to force the HTTPS cloning:
> ```bash
> /plugin marketplace add https://github.com/addyosmani/agent-skills.git
> /plugin install agent-skills@addy-agent-skills
> ```

**Local / development:**

```bash
git clone https://github.com/addyosmani/agent-skills.git
claude --plugin-dir /path/to/agent-skills
```

</details>

<details>
<summary><b>Cursor</b></summary>

Copy any `SKILL.md` into `.cursor/rules/`, or reference the full `skills/` directory. See [docs/cursor-setup.md](docs/cursor-setup.md).

</details>

<details>
<summary><b>Antigravity CLI</b></summary>

Install as a native plugin for skills, subagents, and slash commands. See [docs/antigravity-setup.md](docs/antigravity-setup.md).

**Install from the repo:**

```bash
agy plugin install https://github.com/addyosmani/agent-skills.git
```

**Install from a local clone:**

```bash
git clone https://github.com/addyosmani/agent-skills.git
agy plugin install ./agent-skills
```

</details>

<details>
<summary><b>Gemini CLI</b></summary>

Install as native skills for auto-discovery, or add to `GEMINI.md` for persistent context. See [docs/gemini-cli-setup.md](docs/gemini-cli-setup.md).

**Install from the repo:**

```bash
gemini skills install https://github.com/addyosmani/agent-skills.git --path skills
```

**Install from a local clone:**

```bash
gemini skills install ./agent-skills/skills/
```

</details>

<details>
<summary><b>Windsurf</b></summary>

Add skill contents to your Windsurf rules configuration. See [docs/windsurf-setup.md](docs/windsurf-setup.md).

</details>

<details>
<summary><b>OpenCode</b></summary>

Uses agent-driven skill execution via AGENTS.md and the `skill` tool.

See [docs/opencode-setup.md](docs/opencode-setup.md).

</details>

<details>
<summary><b>GitHub Copilot</b></summary>

Use agent definitions from `agents/` as Copilot personas and skill content in `.github/copilot-instructions.md`. See [docs/copilot-setup.md](docs/copilot-setup.md).

</details>

<details>
  <summary><b>Kiro IDE & CLI </b></summary>
  Skills for Kiro reside under ".kiro/skills/" and can be stored under Project or Global level. Kiro also supports Agents.md. See Kiro docs at https://kiro.dev/docs/skills/
</details>

<details>
<summary><b>Codex / Other Agents</b></summary>

Skills are plain Markdown - they work with any agent that accepts system prompts or instruction files. See [docs/getting-started.md](docs/getting-started.md).

</details>



---

## All 24 Skills

The commands above are entry points. The pack includes 24 skills total — 23 lifecycle skills plus the `using-agent-skills` meta-skill. Each skill is a structured workflow with steps, verification gates, and anti-rationalization tables. You can also reference any skill directly.

### Meta - Discover which skill applies

| Skill | What It Does | Use When |
|-------|-------------|----------|
| [using-agent-skills](skills/using-agent-skills/SKILL.md) | Maps incoming work to the right skill workflow and defines shared operating rules | Starting a session or deciding which skill applies |

### Define - Clarify what to build

| Skill | What It Does | Use When |
|-------|-------------|----------|
| [interview-me](skills/interview-me/SKILL.md) | One-question-at-a-time interview that extracts what the user actually wants instead of what they think they should want, until ~95% confidence | The ask is underspecified, or the user invokes "interview me" / "grill me" |
| [idea-refine](skills/idea-refine/SKILL.md) | Structured divergent/convergent thinking to turn vague ideas into concrete proposals | You have a rough concept that needs exploration |
| [spec-driven-development](skills/spec-driven-development/SKILL.md) | Write a PRD covering objectives, commands, structure, code style, testing, and boundaries before any code | Starting a new project, feature, or significant change |

### Plan - Break it down

| Skill | What It Does | Use When |
|-------|-------------|----------|
| [planning-and-task-breakdown](skills/planning-and-task-breakdown/SKILL.md) | Decompose specs into small, verifiable tasks with acceptance criteria and dependency ordering | You have a spec and need implementable units |

### Build - Write the code

| Skill | What It Does | Use When |
|-------|-------------|----------|
| [incremental-implementation](skills/incremental-implementation/SKILL.md) | Thin vertical slices - implement, test, verify, commit. Feature flags, safe defaults, rollback-friendly changes | Any change touching more than one file |
| [test-driven-development](skills/test-driven-development/SKILL.md) | Red-Green-Refactor, test pyramid (80/15/5), test sizes, DAMP over DRY, Beyonce Rule, browser testing | Implementing logic, fixing bugs, or changing behavior |
| [context-engineering](skills/context-engineering/SKILL.md) | Feed agents the right information at the right time - rules files, context packing, MCP integrations | Starting a session, switching tasks, or when output quality drops |
| [source-driven-development](skills/source-driven-development/SKILL.md) | Ground every framework decision in official documentation - verify, cite sources, flag what's unverified | You want authoritative, source-cited code for any framework or library |
| [doubt-driven-development](skills/doubt-driven-development/SKILL.md) | Adversarial fresh-context review of every non-trivial decision in-flight - CLAIM → EXTRACT → DOUBT → RECONCILE → STOP, with optional user-authorized cross-model escalation | Stakes are high (production, security, irreversible), working in unfamiliar code, or a confident output is cheaper to verify now than to debug later |
| [frontend-ui-engineering](skills/frontend-ui-engineering/SKILL.md) | Component architecture, design systems, state management, responsive design, WCAG 2.1 AA accessibility | Building or modifying user-facing interfaces |
| [api-and-interface-design](skills/api-and-interface-design/SKILL.md) | Contract-first design, Hyrum's Law, One-Version Rule, error semantics, boundary validation | Designing APIs, module boundaries, or public interfaces |

### Verify - Prove it works

| Skill | What It Does | Use When |
|-------|-------------|----------|
| [browser-testing-with-devtools](skills/browser-testing-with-devtools/SKILL.md) | Chrome DevTools MCP for live runtime data - DOM inspection, console logs, network traces, performance profiling | Building or debugging anything that runs in a browser |
| [debugging-and-error-recovery](skills/debugging-and-error-recovery/SKILL.md) | Five-step triage: reproduce, localize, reduce, fix, guard. Stop-the-line rule, safe fallbacks | Tests fail, builds break, or behavior is unexpected |

### Review - Quality gates before merge

| Skill | What It Does | Use When |
|-------|-------------|----------|
| [code-review-and-quality](skills/code-review-and-quality/SKILL.md) | Five-axis review, change sizing (~100 lines), severity labels (Nit/Optional/FYI), review speed norms, splitting strategies | Before merging any change |
| [code-simplification](skills/code-simplification/SKILL.md) | Chesterton's Fence, Rule of 500, reduce complexity while preserving exact behavior | Code works but is harder to read or maintain than it should be |
| [security-and-hardening](skills/security-and-hardening/SKILL.md) | OWASP Top 10 prevention, auth patterns, secrets management, dependency auditing, three-tier boundary system | Handling user input, auth, data storage, or external integrations |
| [performance-optimization](skills/performance-optim