# API And Interface Design (agent skill)

> API And Interface Design is an agent skill (a SKILL.md file) from addyosmani/agent-skills. Guides stable API and interface design. Use when designing APIs, module boundaries, or any public interface. It works with Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot and OpenCode and has 102,166 GitHub stars across a repository of 13 listed skills.

Guides stable API and interface design. Use when designing APIs, module boundaries, or any public interface. Use when creating REST or GraphQL endpoints, defining type contracts between modules, or establishing boundaries between frontend and backend. Design stable, well-documented interfaces that are hard to misuse. Good interfaces make the right thing easy and the wrong thing hard.

## Key facts

| Fact | Value |
|---|---|
| Repository | https://github.com/addyosmani/agent-skills |
| Skill path | skills/api-and-interface-design/SKILL.md |
| Skill name | api-and-interface-design |
| GitHub stars | 102,166 |
| Installs on skills.sh | 903 |
| License | MIT |
| Skills in repo | 13 |
| Plugin marketplace | addy-agent-skills |
| Official | no |
| Works with | Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode |
| Category | Design & frontend |
| Last commit | Oct 3, 2026 |

## When it triggers

- Use when designing APIs, module boundaries, or any public interface.
- Use when creating REST or GraphQL endpoints, defining type contracts between modules, or establishing boundaries between frontend and backend.

## Add this skill

### Claude Code

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

In the Claude apps, zip the skill folder and upload it under Customize > Skills > + > Upload a skill (code execution must be on).

### ChatGPT / Codex

```sh
git clone --depth 1 https://github.com/addyosmani/agent-skills.git
cp -r agent-skills/skills/api-and-interface-design .agents/skills/api-and-interface-design   # repo; ~/.agents/skills for all projects
```

### Cursor

```sh
git clone --depth 1 https://github.com/addyosmani/agent-skills.git
cp -r agent-skills/skills/api-and-interface-design .cursor/skills/api-and-interface-design   # project; ~/.cursor/skills for all projects
```

Sources (checked 2026-10-07): https://code.claude.com/docs/en/skills, https://support.claude.com/en/articles/12512180-using-skills-in-claude, https://learn.chatgpt.com/docs/build-skills, https://cursor.com/docs/context/skills

skills.sh listing: https://www.skills.sh/addyosmani/agent-skills/api-and-interface-design

---

Canonical page: https://appsgit.com/skills/addyosmani-api-and-interface-design
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