What is codexkit-api-design-reviewer?

A review guide for REST and GraphQL APIs, which are ways for software systems to communicate. It checks how an API names resources, handles versions, reports errors, paginates results, authenticates users, and manages breaking changes.

Use it to review an OpenAPI or Swagger specification, design a new API, audit existing endpoints, or prepare an API for outside partners.

It helps find confusing or inconsistent API decisions before they reach users or become expensive to change.

codexkit-api-design-reviewer — Skill for Codex by hoavdc/CodexKit

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.

Any agent

npx skills add hoavdc/CodexKit --skill codexkit-api-design-reviewer

Clone the repo

git clone --depth 1 https://github.com/hoavdc/CodexKit

Made for: Codex.

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/skills/hoavdc/codexkit/codexkit-api-design-reviewer/github.svg)](https://agentmods.dev/skills/hoavdc/codexkit/codexkit-api-design-reviewer)

Your own site

<a href="https://agentmods.dev/skills/hoavdc/codexkit/codexkit-api-design-reviewer"><img src="https://agentmods.dev/badge/skills/hoavdc/codexkit/codexkit-api-design-reviewer/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/skills/hoavdc/codexkit/codexkit-api-design-reviewer"><img src="https://agentmods.dev/badge/skills/hoavdc/codexkit/codexkit-api-design-reviewer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,382 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	$0.00060	$0.01382
Opus 5.5	$0.00024	$0.00553
Sonnet 5.5	$0.00012	$0.00276
Haiku 4.5	$0.00006	$0.00138

Measured 2mo ago against content hash c5e9a683a875, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

codexkit-api-design-reviewer 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 2mo 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.

skills/codexkit-api-design-reviewer/SKILL.md · 167 lines

How it starts

The opening of the file, as written. The whole thing — 167 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Design Reviewer

When to Use

When reviewing an OpenAPI/Swagger specification before implementation
When auditing existing API endpoints for consistency
When designing a new API from scratch
When preparing APIs for external/partner consumption

Procedure

Step 1 — Naming & Convention Check

Check	Rule	Example
Resource naming	Plural nouns, kebab-case	✅ `/api/v1/order-items` ❌ `/api/v1/getOrderItem`
HTTP methods	GET=read, POST=create, PUT=replace, PATCH=partial, DELETE=remove	✅ `POST /orders` ❌ `POST /create-order`
Query params	camelCase for filters/sorting	✅ `?sortBy=createdAt` ❌ `?sort_by=created_at`
Status codes	Use standard codes correctly	✅ 201 Created, 204 No Content ❌ 200 for everything
Consistency	Same pattern across all endpoints	Check all resources follow same naming

Step 2 — Versioning Strategy

Strategy	When to Use	Pattern
URL path	Simple, widely adopted	`/api/v1/orders`
Header	Cleaner URLs, harder to test	`Accept: application/vnd.api+json;version=1`
Query param	Easy to test, but less RESTful	`/api/orders?version=1`

Verify:

Version is present in all endpoints
Deprecation policy documented
Migration guide for version bumps

Step 3 — Error Format

Errors should follow a consistent structure:

{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Human-readable description",
    "details": [
      {
        "field": "email",
        "issue": "Invalid format",
        "expected": "Valid email address"
      }
    ],
    "request_id": "req_abc123",
    "docs_url": "https://docs.api.com/errors/VALIDATION_ERROR"
  }
}

Check:

Error format consistent across all endpoints
Machine-readable error codes (not just messages)
Request ID for traceability
No sensitive data in error responses

Step 4 — Pagination

Pattern	Best For	Implementation
Cursor-based	Large datasets, real-time data	`?cursor=abc&limit=20`
Offset-based	Simple lists, admin UIs	`?page=2&per_page=20`
Keyset	Time-series data	`?after=2024-03-15T00:00:00Z&limit=20`

Read the full file on GitHub · 167 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

agents/openai.yaml 170 B

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.

2mo ago First seen · 167 lines · 60 tokens per session scan A c5e9a683a875

Subscribe to this mod's changes

codexkit-api-design-reviewer is a skill published in the GitHub repository hoavdc/CodexKit (26 stars, last pushed 28d ago), licensed MIT. It adds 60 tokens to every session and 1,382 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.

Backend and APIs ai ai-agents ai-assistant codex codex-cli codex-external review

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