code-review-api

A code-review guide for REST and HTTP APIs—the web interfaces that let software exchange requests and responses.

In plain words
What is it for?
Use it to review API routes, controllers, and request handlers, including validation, pagination, versioning, rate limiting, and operation choice.
Why use it?
It helps find incorrect status codes, unsafe or unclear input handling, inconsistent errors, authentication gaps, and problems with repeated requests or large result sets.

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/andr-ca/agentharness/code-review-api
Clone the repo
git clone --depth 1 https://github.com/andr-ca/agentharness

Made for: Cursor.

Per session 51 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,034 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00051 $0.01034
Opus 5 $0.00026 $0.00517
Sonnet 5 $0.00010 $0.00207
Haiku 4.5 $0.00005 $0.00103

Measured 2d ago against content hash 74ce82fe9e96, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

code-review-api 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/code-review-api.mdc · 55 lines

How it starts

The opening of the file, as written. The whole thing — 55 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Code Review — REST / HTTP API Layer

Focus on correctness, consistency, and safety at the HTTP boundary.

HTTP Semantics

  • Correct status codes201 Created for POST that creates; 200 OK for updates; 204 No Content for DELETE; 400 Bad Request for invalid input; 404 Not Found for missing resources; 409 Conflict for duplicate creation; 422 Unprocessable Entity for validation failures; 500 Internal Server Error for unhandled exceptions.
  • Non-idempotent PUT — PUT must be idempotent (same request = same result). If the operation has side effects that shouldn't repeat, it should be a POST.
  • DELETE returns a body — RFC 7231 allows it, but clients often discard it. Prefer 204 No Content unless returning the deleted resource is explicitly needed.
  • Wrong method for the operation — using GET for state-changing operations (no caching, logging of query params); using POST when PUT/PATCH is more appropriate.

Input Validation & Error Shapes

  • Missing input validation — user-supplied fields used directly without type/range/pattern validation. Every boundary input must be validated before use.
  • Inconsistent error shape — some errors return {"error": "..."}, others {"message": "..."}. The API should follow one schema (RFC 9457 Problem Details recommended).
  • Stack trace in production response — never send exception stack traces to clients. Log server-side; return a stable error code.
  • Leaking internal IDs — returning auto-increment integer IDs exposes row count; prefer UUIDs or opaque tokens.

Authentication & Authorization

  • Auth happens after the operation — authorization must be checked before the DB query, not after loading the resource.
  • Missing ownership check — user can access /orders/123 even if order 123 belongs to another user. Every resource access needs an ownership/permission check.
  • Token in URL — never put auth tokens in query strings (they appear in logs, referrer headers, browser history). Use Authorization header.
  • Missing rate limiting — unauthenticated endpoints or auth endpoints (login, signup) with no rate limit are trivially brute-forced or scraped.

Read the full file on GitHub · 55 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.

  1. 2d ago First seen · 55 lines · 51 tokens per session scan A 74ce82fe9e96

Subscribe to this mod's changes

code-review-api is a cursor rule published in the GitHub repository andr-ca/agentharness (1 stars, last pushed 2d ago), licensed MIT. It adds 51 tokens to every session and 1,034 once invoked, about $0.0003 per session on Opus 5. 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 2026-08-31.