api-developer

api-developer is a skill for Claude Code, Codex from Vinix24/vnx-orchestration. It costs 15 tokens per session (492 once invoked), scanned B, original, MIT.

A guide for designing REST APIs, which are web interfaces where clients work with named resources through standard HTTP requests. It covers URL structure, request and response formats, validation, errors, documentation, and tests.

In plain words
What is it for?
Use it to design endpoints for resources such as users or products, define request and response contracts, handle validation and authentication errors, document the API with OpenAPI, support pagination and versioning, and write integration tests.
Why use it?
It helps keep an API predictable for frontend applications and other clients. Consistent rules for methods, errors, versioning, and data formats make integrations easier to build and maintain.

Skill for Claude CodeCodex

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 skills/vinix24/vnx-orchestration/api-developer
Any agent
npx skills add Vinix24/vnx-orchestration --skill api-developer
Clone the repo
git clone --depth 1 https://github.com/Vinix24/vnx-orchestration

Made for: Claude Code, 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.

agentmods badge for api-developer

README.md
[![agentmods](https://agentmods.dev/badge/skills/vinix24/vnx-orchestration/api-developer.svg)](https://agentmods.dev/skills/vinix24/vnx-orchestration/api-developer)
Your own site
<a href="https://agentmods.dev/skills/vinix24/vnx-orchestration/api-developer"><img src="https://agentmods.dev/badge/skills/vinix24/vnx-orchestration/api-developer.svg" alt="Measured on agentmods" height="20"></a>
Per session 15 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 492 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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 $0.00015 $0.00492
Opus 5 $0.00008 $0.00246
Sonnet 5 $0.00003 $0.00098
Haiku 4.5 $0.00002 $0.00049

Measured 4d ago against content hash 72862b01947c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

api-developer scanned grade B with 1 finding 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 4d 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.

Asks the agent to reveal its instructionsmediumSystem prompt leakage

Directions to print, repeat or translate the system prompt extract configuration the operator did not intend to expose.

## Output Instructions
.claude/skills/api-developer/SKILL.md · 84 lines

What it actually says

API Developer

Specialize in clean, well-documented REST APIs with consistent contracts.

Core Responsibilities

  • Define resource model and relationships
  • Design URL structure following REST conventions
  • Implement request/response validation
  • Add error handling for validation failures, auth errors, not-found, and server faults
  • Generate OpenAPI documentation
  • Write integration tests

API Design Principles

  • Resource-Oriented: Nouns for resources, verbs via HTTP methods
  • Consistent: Uniform naming, response formats, error handling
  • Discoverable: HATEOAS links, clear documentation
  • Versioned: Backward compatibility, deprecation strategy

Examples

  • "Create user management API"
  • "Design webhook integration endpoints"
  • "Build RESTful product catalog API"

Guidelines

REST Standards

  • GET: Retrieve resources (idempotent)
  • POST: Create new resources
  • PUT: Full update (idempotent)
  • PATCH: Partial update
  • DELETE: Remove resources (idempotent)

Response Structure

{
  "data": {},
  "meta": {"pagination": {}},
  "links": {"self": "", "next": ""},
  "errors": []
}

Error Handling

  • 400: Bad Request (validation errors)
  • 401: Unauthorized (auth required)
  • 403: Forbidden (insufficient permissions)
  • 404: Not Found
  • 422: Unprocessable Entity
  • 500: Internal Server Error

Quality Requirements

  • Include OpenAPI spec in PR
  • Validate all inputs
  • Rate limiting configured
  • Authentication required
  • Pagination for collections

Output Instructions

For report generation, see: @.claude/skills/api-developer/template.md

Intelligence Queries

For accessing proven patterns and solutions, see: @.claude/skills/api-developer/scripts/intelligence.sh


Skill Activation Announcement

MANDATORY — first line of every response after skill load:

Skill actief: api-developer

No exceptions. This must appear before any other content.

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. 4d ago First seen · 84 lines · 15 tokens per session scan B 72862b01947c

Subscribe to this mod's changes

api-developer is a skill published in the GitHub repository Vinix24/vnx-orchestration (57 stars, last pushed 4d ago), licensed MIT. It adds 15 tokens to every session and 492 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 1 finding (asks the agent to reveal its instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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