api-design

A set of development rules for REST APIs, which are web interfaces that let software exchange data using standard requests. It covers URL routes and response formats.

In plain words
What is it for?
Use it when defining REST API routes, choosing response formats, and applying API design conventions.
Why use it?
It gives developers a shared way to design APIs, reducing inconsistent routes and data responses.

Cursor rule for Cursor

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.

agentmods
npx agentmods add rules/xin-lai/codespirit/api-design
Clone the repo
git clone --depth 1 https://github.com/xin-lai/CodeSpirit

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 2,085 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.02085
Opus 5 $0.00000 $0.01043
Sonnet 5 $0.00000 $0.00417
Haiku 4.5 $0.00000 $0.00209

Measured 2d ago against content hash b2d92f7c92f8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 2d 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/api-design.mdc · 268 lines

The source is not reproduced here

Licensed AGPL-3.0

The repository is licensed AGPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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.

  1. 2d ago First seen · 268 lines · 0 tokens per session scan A b2d92f7c92f8

Subscribe to this mod's changes

api-design is a cursor rule published in the GitHub repository xin-lai/CodeSpirit (56 stars, last pushed 5mo ago), licensed AGPL-3.0. It costs nothing until one of its globs matches a file; then it loads 2,085 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 2026-08-30.