openapi-gen

openapi-gen is a skill for Claude Code, Codex from berkcangumusisik/claude-code-practices. It costs 18 tokens per session (353 once invoked), scanned A, original, MIT.

A tool that builds an OpenAPI 3.0 description from existing application routes. OpenAPI is a standard document describing an HTTP API, including its URLs, inputs, outputs, and authentication.

In plain words
What is it for?
It helps inspect routes, record parameters and data formats, describe login requirements, and create an openapi.yaml file for tools such as Swagger UI, Postman, or client generators.
Why use it?
It removes the need to document every endpoint by hand and keeps the API description tied to the routes already in the code.

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/berkcangumusisik/claude-code-practices/openapi-gen
Any agent
npx skills add berkcangumusisik/claude-code-practices --skill openapi-gen
Clone the repo
git clone --depth 1 https://github.com/berkcangumusisik/claude-code-practices

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 openapi-gen

README.md
[![agentmods](https://agentmods.dev/badge/skills/berkcangumusisik/claude-code-practices/openapi-gen.svg)](https://agentmods.dev/skills/berkcangumusisik/claude-code-practices/openapi-gen)
Your own site
<a href="https://agentmods.dev/skills/berkcangumusisik/claude-code-practices/openapi-gen"><img src="https://agentmods.dev/badge/skills/berkcangumusisik/claude-code-practices/openapi-gen.svg" alt="Measured on agentmods" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 353 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 $0.00018 $0.00353
Opus 5 $0.00009 $0.00177
Sonnet 5 $0.00004 $0.00071
Haiku 4.5 $0.00002 $0.00035

Measured 5d ago against content hash 8ffa06e155a4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

openapi-gen 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 5d 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/openapi-gen/SKILL.md · 56 lines

What it actually says

Generate OpenAPI Specification

  1. Find all routes:
grep -rn "router\.\|app\." src/ --include="*.ts" | grep -E "\.(get|post|put|patch|delete)\(" | head -40
  1. For each route, extract:

    • HTTP method and path
    • Path parameters (:id, :slug)
    • Query parameters (from validation schema)
    • Request body schema (from Zod/TypeScript types)
    • Response schema
    • Auth requirement
  2. Generate openapi.yaml:

openapi: 3.0.3
info:
  title: API Name
  version: 1.0.0
paths:
  /users:
    get:
      summary: List users
      security:
        - bearerAuth: []
      parameters:
        - name: page
          in: query
          schema: { type: integer, default: 1 }
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/UserList'
  1. Add components/schemas for all reusable types.

  2. Add security schemes (bearerAuth, apiKey, etc.)

  3. Save to openapi.yaml or docs/openapi.yaml.

Tip: This file can be used with Swagger UI, Postman, or client SDK generators.

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. 5d ago First seen · 56 lines · 18 tokens per session scan A 8ffa06e155a4

Subscribe to this mod's changes

openapi-gen is a skill published in the GitHub repository berkcangumusisik/claude-code-practices (10 stars, last pushed 4mo ago), licensed MIT. It adds 18 tokens to every session and 353 once invoked, about $0.0001 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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