# API Shape Explorer

Generate multiple radically different interface designs for a module using parallel...

- Repository: https://github.com/zebbern/claude-code-guide (4691 stars)
- Category: Design
- License: MIT
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add zebbern/claude-code-guide --skill api-shape-explorer -g -a claude-code -y`
Codex: `npx skills add zebbern/claude-code-guide --skill api-shape-explorer -g -a codex -y`
Cursor: `npx skills add zebbern/claude-code-guide --skill api-shape-explorer -g -a cursor -y`
Gemini CLI: `npx skills add zebbern/claude-code-guide --skill api-shape-explorer -g -a gemini-cli -y`

## Description

Generate multiple radically different interface designs for a module using parallel sub-agents. Use when user wants to design an API, explore interface options, compare module shapes, or mentions "design it twice".

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Design an Interface

Based on "Design It Twice" from "A Philosophy of Software Design": your first idea is unlikely to be the best. Generate multiple radically different designs, then compare.

## Workflow

### 1. Gather Requirements

Before designing, understand:

- [ ] What problem does this module solve?
- [ ] Who are the callers? (other modules, external users, tests)
- [ ] What are the key operations?
- [ ] Any constraints? (performance, compatibility, existing patterns)
- [ ] What should be hidden inside vs exposed?

Ask: "What does this module need to do? Who will use it?"

### 2. Generate Designs (Parallel Sub-Agents)

Spawn 3+ sub-agents simultaneously using Task tool. Each must produce a **radically different** approach.

```
Prompt template for each sub-agent:

Design an interface for: [module description]

Requirements: [gathered requirements]

Constraints for this design: [assign a different constraint to each agent]
- Agent 1: "Minimize method count - aim for 1-3 methods max"
- Agent 2: "Maximize flexibility - support many use cases"
- Agent 3: "Optimize for the most common case"
- Agent 4: "Take inspiration from [specific paradigm/library]"

Output format:
1. Interface signature (types/methods)
2. Usage example (how caller uses it)
3. What this design hides internally
4. Trade-offs of this approach
```

### 3. Present Designs

Show each design with:

1. **Interface signature** - types, methods, params
2. **Usage examples** - how callers actually use it in practice
3. **What it hides** - complexity kept internal

Present designs sequentially so user can absorb each approach before comparison.

### 4. Compare Designs

After showing all designs, compare them on:

The rest: https://github.com/zebbern/claude-code-guide/blob/HEAD/skills/api-shape-explorer/SKILL.md