api-design

api-design is a skill for Claude Code, Codex from srstomp/pokayokay. It costs 38 tokens per session (599 once invoked), scanned A, original, MIT.

Guidance for designing REST APIs, web interfaces that let programs exchange data using standard HTTP requests. It covers URLs, data formats, pagination, versioning, authentication, and OpenAPI documentation.

In plain words
What is it for?
Use it to plan resources and operations, define request and response data, standardize errors, design authentication flows, and document the API.
Why use it?
It helps keep an API predictable and understandable for the developers who use and maintain it.

Skill for Claude CodeCodex

Part of the pokayokay plugin — 17 skills, 23 commands, 14 agents, 4 hooks, 1 MCP server shipped together

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/srstomp/pokayokay/api-design
Any agent
npx skills add srstomp/pokayokay --skill api-design
Clone the repo
git clone --depth 1 https://github.com/srstomp/pokayokay

Made for: Claude Code, Codex.

Or install pokayokay, the plugin that ships this one along with the rest of its 17 skills, 23 commands, 14 agents, 4 hooks, 1 MCP server.

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-design

README.md
[![agentmods](https://agentmods.dev/badge/skills/srstomp/pokayokay/api-design.svg)](https://agentmods.dev/skills/srstomp/pokayokay/api-design)
Your own site
<a href="https://agentmods.dev/skills/srstomp/pokayokay/api-design"><img src="https://agentmods.dev/badge/skills/srstomp/pokayokay/api-design.svg" alt="Measured on agentmods" height="20"></a>
Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 599 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 $0.00038 $0.00599
Opus 5 $0.00019 $0.00300
Sonnet 5 $0.00008 $0.00120
Haiku 4.5 $0.00004 $0.00060

Measured 3d ago against content hash 2d0ce57f993c, 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 3d 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.

plugins/pokayokay/skills/api-design/SKILL.md · 56 lines

How it starts

The opening of the file, as written. The whole thing — 56 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Design

Design clear, consistent, and developer-friendly REST APIs.

When NOT to Use

  • Consuming external APIs — Use api-integration for building clients to call third-party services (Stripe, Twilio, etc.)
  • Writing tests for APIs — Use testing-strategy for contract tests, integration tests, mocking strategies
  • Reviewing existing API security — Use security-audit for vulnerability scanning of live endpoints
  • Designing auth mechanisms that are the whole task — Use security-audit if reviewing, this skill if designing from scratch

Core Principles

  • Resource-oriented — Design around nouns (resources), not verbs (actions)
  • Predictable patterns — Consistent URL structure, response format, and behavior
  • Clear contracts — Explicit schemas, documented errors, versioned endpoints
  • Developer experience — Meaningful errors, helpful examples, logical defaults

Quick Start Checklist

  1. Identify resources and their relationships
  2. Define CRUD operations + custom actions with correct HTTP methods
  3. Design request/response schemas with consistent envelope
  4. Plan error format with status codes, error codes, and field-level details
  5. Write OpenAPI specification with examples
  6. Review for consistency, security, and usability

Design Quick Reference

Method Purpose Idempotent Body
GET Read Yes No
POST Create No Yes
PUT Replace Yes Yes
PATCH Partial update Yes* Yes
DELETE Remove Yes No

References

Reference Description
endpoints.md URL design, HTTP methods, resource modeling
requests-responses.md Request/response formats, headers, content types
status-codes.md HTTP status codes, error handling patterns
pagination-filtering.md Pagination, filtering, sorting, searching
versioning.md API versioning strategies
openapi.md OpenAPI specification, documentation
security.md Authentication, authorization, rate limiting
tdd-patterns.md Test-first patterns for REST endpoints, supertest templates
review-checklist.md API design review checklist (validation, auth, performance, docs)

Read the full file on GitHub · 56 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. 3d ago First seen · 56 lines · 38 tokens per session scan A 2d0ce57f993c

Subscribe to this mod's changes

api-design is a skill published in the GitHub repository srstomp/pokayokay (9 stars, last pushed 2mo ago), licensed MIT. It adds 38 tokens to every session and 599 once invoked, about $0.0002 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.

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