What is openapi-expert?

A reference guide for OpenAPI, a machine-readable description of a web API, often written in YAML or JSON. It covers endpoints, inputs, outputs, data shapes, and security rules.

Use it to design REST APIs, document requests and responses, define reusable data models, describe authentication, validate APIs, and support code generation.

It helps keep an API's documentation, validation, tests, and generated client or server code based on the same contract.

openapi-expert — Skill for Claude Code by personamanagmentlayer/pcl

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 personamanagmentlayer/pcl --skill openapi-expert

Clone the repo

git clone --depth 1 https://github.com/personamanagmentlayer/pcl

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/personamanagmentlayer/pcl/openapi-expert/github.svg)](https://agentmods.dev/skills/personamanagmentlayer/pcl/openapi-expert)

Your own site

<a href="https://agentmods.dev/skills/personamanagmentlayer/pcl/openapi-expert"><img src="https://agentmods.dev/badge/skills/personamanagmentlayer/pcl/openapi-expert/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/personamanagmentlayer/pcl/openapi-expert"><img src="https://agentmods.dev/badge/skills/personamanagmentlayer/pcl/openapi-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 985 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. Third-party audits

NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium MCP Rug Pull · line 148
Docker image references without a specific tag (:latest is implicit) or digest (@sha256:...) can be silently replaced by a malicious image.

Fix: Pin the image: image:tag or image@sha256:abc123
medium MCP Rug Pull · line 154
Docker image references without a specific tag (:latest is implicit) or digest (@sha256:...) can be silently replaced by a malicious image.

Fix: Pin the image: image:tag or image@sha256:abc123

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00057	$0.00985
Opus 5.5	$0.00023	$0.00394
Sonnet 5.5	$0.00011	$0.00197
Haiku 4.5	$0.00006	$0.00098

Measured 1mo ago against content hash 4ac6f8609c2f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

openapi-expert 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 1mo 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.

stdlib/api/openapi-expert/SKILL.md · 185 lines

How it starts

The opening of the file, as written. The whole thing — 185 lines — stays where its author put it; the contents beside it link to each section on GitHub.

OpenAPI Expert

Expert guidance for OpenAPI Specification (formerly Swagger) - industry-standard for describing RESTful APIs with automatic documentation and code generation.

Core Concepts

OpenAPI Specification (OAS)

API description format (YAML/JSON)
Version 3.1 (latest) and 3.0
Machine-readable API contracts
Automatic documentation generation
Client/server code generation
API validation and testing

Key Components

Paths (endpoints)
Operations (HTTP methods)
Parameters
Request/Response bodies
Schemas (data models)
Security schemes
Components (reusable objects)

Advanced Features

Webhooks (OpenAPI 3.1)

webhooks:
  postCreated:
    post:
      summary: Post created webhook
      operationId: onPostCreated
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Post'
      responses:
        '200':
          description: Webhook received

Polymorphism (oneOf/anyOf/allOf)

components:
  schemas:
    Pet:
      oneOf:
        - $ref: '#/components/schemas/Cat'
        - $ref: '#/components/schemas/Dog'
      discriminator:
        propertyName: petType
        mapping:
          cat: '#/components/schemas/Cat'
          dog: '#/components/schemas/Dog'

    Cat:
      allOf:
        - $ref: '#/components/schemas/PetBase'
        - type: object
          properties:
            petType:
              type: string
              enum: [cat]
            meow:
              type: string

    Dog:
      allOf:
        - $ref: '#/components/schemas/PetBase'
        - type: object
          properties:
            petType:
              type: string
              enum: [dog]
            bark:
              type: string

Code Generation

# Install OpenAPI Generator
npm install -g @openapitools/openapi-generator-cli

# Generate TypeScript client
openapi-generator-cli generate \
  -i openapi.yaml \
  -g typescript-axios \
  -o ./client

# Generate Python Flask server
openapi-generator-cli generate \
  -i openapi.yaml \
  -g python-flask \
  -o ./server

# Generate Java Spring server
openapi-generator-cli generate \
  -i openapi.yaml \
  -g spring \
  -o ./server

Read the full file on GitHub · 185 lines

Files

What ships with it

1 file 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.

references/BASIC_OPENAPI_SPECIFICATION.md 7.1 KB

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.

1mo ago Changed · -321 lines · +36 tokens per session 4ac6f8609c2f
1mo ago First seen · 506 lines · 21 tokens per session scan A 83b3a0c9015e

Subscribe to this mod's changes

openapi-expert is a skill published in the GitHub repository personamanagmentlayer/pcl (44 stars, last pushed 8d ago), licensed Apache-2.0. It adds 57 tokens to every session and 985 once invoked, about $0.0002 per session on Opus 5.5. 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.

Backend and APIs Writing and docs anthropic api api-design api-spec claude deepseek documentation gemini generative-ai openapi rest swagger

api-docs-generator

Generate API documentation from code - produce OpenAPI/Swagger specs, Markdown API references, request/response examples, and interactive documentation from source code analysis.

chainlesschain/chainlesschain · 34 tokens

openapi-designer

Design complete OpenAPI 3.1 specifications for RESTful APIs. Covers schemas, security, examples, webhooks, and documentation generation.

AtulPurohit/Antigravity-Awesome-Skills · 33 tokens

backend-openapi-documentation

Use this skill when the user says 'OpenAPI', 'Swagger', 'API documentation', 'spec-first', 'API spec', 'openapi.yaml', 'swagger.json', 'codegen', 'openapi-generator', 'API contract first'. This skill enforces spec-first API documentation with OpenAPI 3.x, code generation, and versioned specs. Applies to any backend…

j4flmao/agent-skills · 103 tokens

API Documentation Generator

Generates OpenAPI-compatible documentation for REST API endpoints from code or route definitions.

Notysoty/openagentskills · 20 tokens

api-design

Design REST APIs with consistent naming, error handling, versioning, and pagination. Use when designing a new API, reviewing an existing one, or writing an OpenAPI spec.

chandrudp29/skillhub · 38 tokens

api-documentation-generator

Generates OpenAPI 3.0/3.1 specs, TypeScript client types, and curl examples from existing route handler code. Supports Express, Next.js API routes, Fastify, and Hono. Produces complete documentation including auth requirements, rate limits, error codes, and request/response examples. Activate on: 'generate API docs'…

curiositech/windags-skills · 129 tokens