api-reference-documentation

A guide for writing API reference documentation from OpenAPI specifications, a standard format that describes web API endpoints and data. It includes authentication details, schemas, and examples.

In plain words
What is it for?
Use it to document REST API endpoints, authentication, request parameters, responses, data models, and developer portals.
Why use it?
It turns technical API definitions into documentation that developers can use when connecting their software to an API.

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/secondsky/claude-skills/api-reference-documentation
Any agent
npx skills add secondsky/claude-skills --skill api-reference-documentation
Clone the repo
git clone --depth 1 https://github.com/secondsky/claude-skills

Made for: Claude Code, Codex.

Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 505 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 $0.00037 $0.00505
Opus 5 $0.00018 $0.00253
Sonnet 5 $0.00007 $0.00101
Haiku 4.5 $0.00004 $0.00051

Measured 2d ago against content hash d44d95eca8c8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-reference-documentation 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.

plugins/api-reference-documentation/skills/api-reference-documentation/SKILL.md · 95 lines

What it actually says

API Reference Documentation

Create comprehensive API documentation for developer integration.

OpenAPI 3.0 Specification

openapi: 3.0.3
info:
  title: E-Commerce API
  version: 1.0.0
  description: API for managing products and orders
  contact:
    email: [email protected]

servers:
  - url: https://api.example.com/v1
    description: Production
  - url: https://staging-api.example.com/v1
    description: Staging

security:
  - bearerAuth: []

paths:
  /products:
    get:
      summary: List products
      tags: [Products]
      parameters:
        - name: limit
          in: query
          schema: { type: integer, default: 20 }
        - name: category
          in: query
          schema: { type: string }
      responses:
        '200':
          description: Product list
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProductList'

components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT

  schemas:
    Product:
      type: object
      required: [id, name, price]
      properties:
        id: { type: string, format: uuid }
        name: { type: string, maxLength: 200 }
        price: { type: number, minimum: 0 }
        description: { type: string }

Documentation Checklist

  • All endpoints documented with examples
  • Authentication methods explained
  • Error responses specified
  • Rate limits documented
  • Pagination explained
  • Webhooks documented (if applicable)
  • SDK examples in multiple languages

Best Practices

  • Use OpenAPI 3.0+ specification
  • Include request/response examples
  • Document all parameters and headers
  • Provide authentication examples
  • Enable interactive API exploration
  • Maintain version documentation
  • Include migration guides for breaking changes

Tools

  • Swagger Editor / Swagger UI
  • Redoc
  • Postman Documentation
  • Stoplight
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 · 95 lines · 37 tokens per session scan A d44d95eca8c8

Subscribe to this mod's changes

api-reference-documentation is a skill published in the GitHub repository secondsky/claude-skills (212 stars, last pushed 3d ago), licensed MIT. It adds 37 tokens to every session and 505 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 2026-08-30.

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