A set of conventions for designing REST APIs, which are web interfaces that let software exchange data using standard HTTP requests.

Use it when creating or changing API endpoints, including resource routes, filtering, sorting, pagination, and version changes.

It helps keep endpoint URLs, response formats, versioning, pagination, and HTTP behavior consistent across an API.

api-design — Cursor rule for Cursor by girijashankarj/cursor-handbook

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo

git clone --depth 1 https://github.com/girijashankarj/cursor-handbook

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/rules/girijashankarj/cursor-handbook/api-design/github.svg)](https://agentmods.dev/rules/girijashankarj/cursor-handbook/api-design)

Your own site

<a href="https://agentmods.dev/rules/girijashankarj/cursor-handbook/api-design"><img src="https://agentmods.dev/badge/rules/girijashankarj/cursor-handbook/api-design/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/rules/girijashankarj/cursor-handbook/api-design"><img src="https://agentmods.dev/badge/rules/girijashankarj/cursor-handbook/api-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 775 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00000	$0.00775
Opus 5.5	$0.00000	$0.00310
Sonnet 5.5	$0.00000	$0.00155
Haiku 4.5	$0.00000	$0.00077

Measured 1mo ago against content hash c3b073466d9f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

api-design scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/backend/api-design.mdc · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Design Rules

URL Structure

/api/v{version}/{resource}                    # Collection
/api/v{version}/{resource}/{id}               # Single resource
/api/v{version}/{resource}/{id}/{sub-resource} # Sub-resource

HTTP Methods

Method	Action	Response Code	Idempotent
GET	Read	200	Yes
POST	Create	201	No
PUT	Full update	200	Yes
PATCH	Partial update	200	Yes
DELETE	Soft delete	200	Yes

Response Envelope

{
  "data": {},
  "meta": {
    "correlationId": "abc-123",
    "timestamp": "2026-01-15T10:30:00Z",
    "pagination": {
      "page": 1,
      "pageSize": 20,
      "total": 150,
      "hasNextPage": true,
      "cursor": "eyJpZCI6MTIzfQ=="
    }
  }
}

Versioning

Use URL path versioning: /api/v1/, /api/v2/
Support at most 2 active versions simultaneously
Deprecation notice 6 months before version removal
Document breaking changes in changelog

Query Parameters

Parameter	Purpose	Example
`page`, `pageSize`	Pagination	`?page=2&pageSize=20`
`cursor`	Cursor pagination	`?cursor=abc123`
`sort`	Sorting	`?sort=-created_at,name`
`filter`	Filtering	`?filter[status]=active`
`fields`	Field selection	`?fields=id,name,email`
`include`	Related resources	`?include=items,customer`

Rate Limiting

Include rate limit headers in all responses:
- X-RateLimit-Limit: Max requests per window
- X-RateLimit-Remaining: Remaining requests
- X-RateLimit-Reset: Window reset timestamp
Return 429 when limit exceeded with Retry-After header

Anti-patterns

Don't use 200 for errors — use 4xx/5xx with error body
Don't nest resources > 2 levels — /api/v1/orders/123/items OK; deeper = split
Don't return array without pagination — always paginate list endpoints
Don't use query params for sensitive data — use headers or body
Don't version in headers only — use URL path for cacheability

Read the full file on GitHub · 90 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

1mo ago First seen · 90 lines · 0 tokens per session scan A c3b073466d9f

Subscribe to this mod's changes

api-design is a cursor rule published in the GitHub repository girijashankarj/cursor-handbook (33 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 775 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

Backend and APIs Claude Code claude claude-ai cursor cursor-agents cursor-ai

data-fetching

Data fetching patterns with TanStack Query, Server Components, and Supabase.

kensaurus/cursor-kenji · 0 tokens

full-stack-ship-discipline

Require frontend changes and their DB/RPC/RLS/storage/secret dependencies to ship and be remotely verified together. Apply when implementing code that reads or writes backend state. Do not apply to plan- or present-then-stop audits; production data mutation still requires confirmation.

kensaurus/cursor-kenji · 53 tokens

api-design