api-documentation

A set of methods and templates for documenting web APIs and event-driven APIs. An API is an interface that lets software exchange requests and data; OpenAPI, Swagger, and AsyncAPI are formats for describing those interfaces.

In plain words
What is it for?
Use it to create or review REST API documentation, OpenAPI or Swagger specifications, and AsyncAPI documentation for WebSocket or event-based services.
Why use it?
Incomplete or incorrect API documentation causes integration failures and forces users to discover behaviour by trial and error. The review process checks endpoints, authentication, examples, schemas, and error responses.

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/zircote-plugins/documentation-review/api-documentation
Any agent
npx skills add zircote-plugins/documentation-review --skill api-documentation
Clone the repo
git clone --depth 1 https://github.com/zircote-plugins/documentation-review

Made for: Claude Code, Codex.

Per session 163 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,519 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 $0.00163 $0.02519
Opus 5 $0.00081 $0.01260
Sonnet 5 $0.00033 $0.00504
Haiku 4.5 $0.00016 $0.00252

Measured 2d ago against content hash 9c7f1f605a26, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-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.

skills/api-documentation/SKILL.md · 311 lines

How it starts

The opening of the file, as written. The whole thing — 311 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Documentation

API documentation is the contract between your service and its consumers. Incomplete or inaccurate API docs cause integration failures, support tickets, and abandoned adoption. This skill covers REST (OpenAPI), event-driven (AsyncAPI), and language-native API documentation patterns.

Review Workflow

When reviewing existing API documentation, follow this sequence:

  1. Inventory endpoints — scan route handlers/controllers and cross-reference against the spec's paths. Missing endpoints are the most common defect.
  2. Check required elements — for each endpoint, verify all 7 elements below (summary, description, parameters, request body, responses, examples, auth).
  3. Validate examples — request/response examples should be valid JSON matching the declared schemas. Invalid examples break SDK generators and mislead consumers.
  4. Audit error responses — every endpoint should document at least 400, 404 (for resource endpoints), and 500 responses. Missing error docs force consumers to discover failures at runtime.
  5. Verify authentication — security schemes should be defined in components/securitySchemes and applied globally or per-endpoint.
  6. Check the quality checklist at the end of this document for a final pass.

Quick Reference

For copy-paste endpoint templates, see references/endpoint-templates.md. For advanced OpenAPI patterns (discriminators, webhooks, callbacks), see references/openapi-patterns.md. For complete working specs, see examples/petstore-openapi.yaml and examples/events-asyncapi.yaml.

OpenAPI/Swagger Overview

OpenAPI Specification (OAS) is the standard for describing REST APIs. Use it for:

  • Auto-generating documentation portals
  • Client SDK generation
  • API testing and validation
  • Contract-first development

Supported Versions

  • OpenAPI 3.1 - Current standard, JSON Schema compatible
  • OpenAPI 3.0 - Widely supported, stable
  • Swagger 2.0 - Legacy, migrate when feasible since tooling is converging on 3.x

Read the full file on GitHub · 311 lines

Files

What ships with it

5 files 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.

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 · 311 lines · 163 tokens per session scan A 9c7f1f605a26

Subscribe to this mod's changes

api-documentation is a skill published in the GitHub repository zircote-plugins/documentation-review (4 stars, last pushed 2mo ago), licensed MIT. It adds 163 tokens to every session and 2,519 once invoked, about $0.0008 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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