api-designer

api-designer is a skill for Claude Code, Codex from mehdiozdemir/awesome-agent-skills. It costs 52 tokens per session (4,929 once invoked), scanned A, original, MIT.

A guide to designing and reviewing APIs, which are defined ways for software systems to communicate. It covers REST, GraphQL, and gRPC interfaces, including their requests, responses, authentication, and documentation.

In plain words
What is it for?
Use it to create or review endpoints, design API contracts and authentication flows, generate OpenAPI or Swagger specifications, and improve API performance.
Why use it?
It helps keep an API predictable for users and other services, reducing confusing contracts and avoidable integration problems.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create or review endpoints, design API contracts and authentication flows, generate OpenAPI or Swagger specifications, and improve API performance.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mehdiozdemir/awesome-agent-skills/api-designer
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 mehdiozdemir/awesome-agent-skills --skill api-designer
Clone the repo
git clone --depth 1 https://github.com/mehdiozdemir/awesome-agent-skills

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-designer

README.md
[![agentmods](https://agentmods.dev/badge/skills/mehdiozdemir/awesome-agent-skills/api-designer/github.svg)](https://agentmods.dev/skills/mehdiozdemir/awesome-agent-skills/api-designer)
Your own site
<a href="https://agentmods.dev/skills/mehdiozdemir/awesome-agent-skills/api-designer"><img src="https://agentmods.dev/badge/skills/mehdiozdemir/awesome-agent-skills/api-designer/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.

agentmods 80×15 button for api-designer

Your own site · 80×15
<a href="https://agentmods.dev/skills/mehdiozdemir/awesome-agent-skills/api-designer"><img src="https://agentmods.dev/badge/skills/mehdiozdemir/awesome-agent-skills/api-designer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,929 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00052 $0.04929
Opus 5 $0.00026 $0.02465
Sonnet 5 $0.00010 $0.00986
Haiku 4.5 $0.00005 $0.00493

Measured 11d ago against content hash 1f6b75db5eca, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

api-designer 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 11d 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/api-designer/SKILL.md · 906 lines

How it starts

The opening of the file, as written. The whole thing — 906 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Designer Skill

This skill helps design, review, and implement APIs following industry best practices. Use this whenever you need to create new APIs, review existing API designs, generate specifications, or improve API developer experience.

API Design Principles

1. REST API Fundamentals

Principle Description
Resource-Oriented URLs represent resources, not actions
Stateless Each request contains all needed information
Uniform Interface Consistent patterns across endpoints
HATEOAS Responses include navigation links
Cacheable Responses indicate cacheability

2. HTTP Methods

Method Purpose Idempotent Safe Request Body
GET Read resource
POST Create resource
PUT Replace resource
PATCH Partial update
DELETE Remove resource
HEAD Get headers only
OPTIONS Get allowed methods

3. HTTP Status Codes

Success (2xx):

Code Meaning Use Case
200 OK Successful GET, PUT, PATCH
201 Created Successful POST
202 Accepted Async operation started
204 No Content Successful DELETE

Client Errors (4xx):

Code Meaning Use Case
400 Bad Request Invalid input/validation error
401 Unauthorized Missing/invalid authentication
403 Forbidden Valid auth but insufficient permissions
404 Not Found Resource doesn't exist
405 Method Not Allowed Wrong HTTP method
409 Conflict Duplicate/conflict with current state
422 Unprocessable Entity Semantic validation error
429 Too Many Requests Rate limit exceeded

Server Errors (5xx):

Code Meaning Use Case
500 Internal Server Error Unexpected server error
502 Bad Gateway Upstream service error
503 Service Unavailable Maintenance/overload
504 Gateway Timeout Upstream timeout

Read the full file on GitHub · 906 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. 11d ago First seen · 906 lines · 52 tokens per session scan A 1f6b75db5eca

Subscribe to this mod's changes

api-designer is a skill published in the GitHub repository mehdiozdemir/awesome-agent-skills (2 stars, last pushed 7mo ago), licensed MIT. It adds 52 tokens to every session and 4,929 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.

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