# lean-startup

A skill for building under uncertainty: it structures experiments, picks metrics that move, and helps you decide whether to change course.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 665 installs · ★ 776
- Author: getagentseal
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/getagentseal/founder-playbook/tree/HEAD/skills/lean-startup/SKILL.md
- Updated: 2026-10-06
- HTML: https://affpapa.org/en/nevibecode/skills/getagentseal-lean-startup

## What it does

The skill turns Eric Ries's Lean Startup method into concrete steps an agent can follow. It covers the Build-Measure-Learn loop, the two leap-of-faith assumptions (value and growth), MVP types, and the three milestones of innovation accounting: establish a baseline, tune the engine, then pivot or persevere. A table separates vanity metrics from actionable ones — cumulative signups versus signups per cohort, page views versus conversion by step.

The author labels it independent analysis rather than a reproduction of the book, so it folds in modern practice and flags where the original frameworks fall short. Planning runs backwards from the loop's name: decide what you need to learn, work out which data shows it, and build only what produces that data.

The skill also fences off its own scope. Once product/market fit is proven and you're scaling a known playbook, it points you to Crossing the Chasm; market type goes to Four Steps, sales to SPIN Selling, pricing to Monetizing Innovation. That matters if you're past the search stage — the advice here is aimed at uncertainty, not at execution.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add getagentseal/founder-playbook --skill lean-startup -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/lean-startup/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/lean-startup/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add getagentseal/founder-playbook --skill lean-startup -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/lean-startup/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add getagentseal/founder-playbook --skill lean-startup -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/lean-startup/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install getagentseal/founder-playbook lean-startup
```

2. **Manually: put the files in place**
- File: `.github/skills/lean-startup/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add getagentseal/founder-playbook --skill lean-startup -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/getagentseal/founder-playbook --path skills/lean-startup
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/lean-startup/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add getagentseal/founder-playbook --skill lean-startup -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/getagentseal/founder-playbook/tree/HEAD/skills/lean-startup/SKILL.md

## When to use it
- test a product idea before writing code
- design an MVP that checks one assumption
- tell vanity metrics from actionable cohort data
- decide whether to pivot or keep going
- set up innovation accounting instead of revenue forecasts

## Example prompts
- Help me design an MVP: what are we actually testing and what data will show it
- Our metrics look fine but growth stalled — walk through this with lean-startup
- Time to decide: pivot or persevere. Run our progress through innovation accounting

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: e73bf22b195a1841.

BEGIN THIRD-PARTY FILE e73bf22b195a1841
````text
---
name: lean-startup
description: "Applies Eric Ries's Lean Startup methodology for building products under extreme uncertainty. Use when iterating toward product/market fit, designing MVPs, deciding whether to pivot or persevere, setting up actionable metrics, or accelerating the Build-Measure-Learn loop. Triggers include 'how do we test this idea fast', 'what should our MVP look like', 'our metrics look good but we're not growing', 'should we pivot', 'we're building features no one uses', 'how do we measure validated learning', 'vanity metrics vs real metrics', 'how to do innovation accounting'. NOT for companies with proven product/market fit scaling a known playbook (use Crossing the Chasm), not for determining Market Type (use Four Steps), not for sales methodology (use SPIN Selling), not for pricing strategy (use Monetizing Innovation)."
---

> **Note:** This skill is independent analysis and commentary, not a reproduction of the original text. It synthesizes the book's core ideas with modern startup practice, surfaces where frameworks are outdated or incomplete, and integrates perspectives from adjacent disciplines. For the full argument and context, read the original book.


# The Lean Startup

> "The Lean Startup is not a collection of individual tactics. It is a principled approach to new product development." - Eric Ries

## Should You Use This Skill?

```
Are you building something under conditions of extreme uncertainty?
|-- YES --> Do you know who your customers are?
|   |-- NO  --> Start with Four Steps (Customer Discovery), use Lean
|   |           Startup for iteration speed within that process
|   +-- YES --> Do you have product/market fit?
|               |-- NO  --> THIS SKILL. Build-Measure-Learn loop.
|               +-- YES --> Use Crossing the Chasm for mainstream scaling
+-- NO  --> Are you optimizing an existing product in a known market?
            |-- YES --> Lean Startup principles apply (small batches,
            |           Five Whys) but you don't need the full framework
            +-- NO  --> Rethink what you're doing
```

---

## The Core Insight

**Most startups fail not because they can't build a product, but because they build something nobody wants.** The default response to failure is: we didn't plan well enough, execute hard enough, or have the right vision. Ries argues the real problem is the absence of a management framework designed for uncertainty.
````
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