api-and-interface-design SKILL.md skillA

api-and-interface-design from lll0k0lad/agent-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.

mdr add lll0k0lad/agent-skills/api-and-interface-design@git:20260215.af8eb3a

Pins git:20260215.af8eb3a in mdr.lock. Pin the fingerprint instead.

Audit grade

A, 17 of 17 checks passed

Kind

SKILL.md skill

Repository

lll0k0lad/agent-skills

Path

skills/api-and-interface-design/SKILL.md

Versions recorded

1

Latest version

git:20260215.af8eb3a, committed Feb 15, 2026

Size

8,452 bytes

Repository stars

3

License

MIT

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.

Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.

What the file says

# API and Interface Design

## Overview

Design stable, well-documented interfaces that are hard to misuse. Good interfaces make the right thing easy and the wrong thing hard. This applies to REST APIs, GraphQL schemas, module boundaries, component props, and any surface where one piece of code talks to another.

## When to Use

- Designing new API endpoints
- Defining module boundaries or contracts between teams
- Creating component prop interfaces
- Establishing database schema that informs API shape
- Changing existing public interfaces

## Core Principles

### 1. Contract First

Define the interface before implementing it. The contract is the spec — implementation follows.

```typescript
// Define the contract first
interface TaskAPI {
  // Creates a task and returns the created task with server-generated fields
  createTask(input: CreateTaskInput): Promise<Task>;

  // Returns paginated tasks matching filters
  listTasks(params: ListTasksParams): Promise<PaginatedResult<Task>>;

  // Returns a single task or throws NotFoundError
  getTask(id: string): Promise<Task>;

  // Partial update — only provided fields change
…

Read the whole file at its exact version.

How to install

mdr add lll0k0lad/agent-skills/api-and-interface-design@sha256:58c5c117593f2fb8

[![mdr](https://markdownregistry.com/badge/art_2npydy5lbjkurxgp.svg)](https://markdownregistry.com/a/art_2npydy5lbjkurxgp)

Versions

The registry has recorded 1 version of this file, committed on Feb 15, 2026.

Audit of the latest version

Source

API

GET https://markdownregistry.com/api/v1/artifacts/art_2npydy5lbjkurxgp
GET https://markdownregistry.com/api/v1/resolve?ref=lll0k0lad/agent-skills/api-and-interface-design
GET https://markdownregistry.com/api/v1/blob/58c5c117593f2fb88478671e10063ce0027c59c226ae4f4856a15b8a74f85c76

Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.

Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.

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