Design an API contract

---
name: api-contract
description: "Align clients and servers on validation, errors, pagination, and compatibility before coding."
license: CC0-1.0
metadata:
  author: "SI Editorial"
  version: "1"
---

# Design an API contract

## When to use
Align clients and servers on validation, errors, pagination, and compatibility before coding.

## Workflow
1. Read the use case and existing API conventions.
2. Specify resources, methods, inputs, outputs, authorization, idempotency, pagination, and rate limits.
3. Include happy path and failure examples and define which errors clients may retry.
4. Identify breaking changes and propose a migration path.

## Boundaries
Use only tools and data authorized for the task. Ask for missing requirements when they affect the result. Report what you verified and what you could not verify.

## Try it
Design a create-booking API that tolerates retries.

## Success looks like
A reviewable contract with duplicate-request and unauthorized-request examples.