Generate and maintain OpenAPI 3.1 specifications from code, design-first specs, and validation patterns. Use when creating API documentation, generating SDKs, or ensuring API contract compliance.
Install with the open skills CLI (global, non-interactive — available in every Claude Code session):
npx skills add wshobson/agents --skill "openapi-spec-generation" -g -a claude-code -yOr manually — clone and copy the skill directory (SKILL.md + companion files):
git clone --depth 1 https://github.com/wshobson/agents /tmp/agents && cp -r /tmp/agents/plugins/documentation-generation/skills/openapi-spec-generation ~/.claude/skills/openapi-spec-generation-wshobsonThis skill is a directory: SKILL.md is the entry point; the files below ship with it.
---
name: openapi-spec-generation
description: Generate and maintain OpenAPI 3.1 specifications from code, design-first specs, and validation patterns. Use when creating API documentation, generating SDKs, or ensuring API contract compliance.
---
# OpenAPI Spec Generation
Comprehensive patterns for creating, maintaining, and validating OpenAPI 3.1 specifications for RESTful APIs.
## When to Use This Skill
- Creating API documentation from scratch
- Generating OpenAPI specs from existing code
- Designing API contracts (design-first approach)
- Validating API implementations against specs
- Generating client SDKs from specs
- Setting up API documentation portals
## Core Concepts
### 1. OpenAPI 3.1 Structure
```yaml
openapi: 3.1.0
info:
title: API Title
version: 1.0.0
servers:
- url: https://api.example.com/v1
paths:
/resources:
get: ...
components:
schemas: ...
securitySchemes: ...
```
### 2. Design Approaches
| Approach | Description | Best For |
| ---------------- | ---------------------------- | ------------------- |
| **Design-First** | Write spec before code | New APIs, contracts |
| **Code-First** | Generate spec from code | Existing APIs |
| **Hybrid** | Annotate code, generate spec | Evolving APIs |
## Templates and detailed worked examples
Full template library and detailed worked examples live in `references/details.md`. Read that file when you need the concrete templates.
## Best Practices
### Do's
- **Use $ref** - Reuse schemas, parameters, responses
- **Add examples** - Real-world values help consumers
- **Document errors** - All possible error codes
- **Version your API** - In URL or header
- **Use semantic versioning** - For spec changes
### Don'ts
- **Don't use generic descriptions** - Be specific
- **Don't skip security** - Define all schemes
- **Don't forget nullable** - Be explicit about null
- **Don't mix styles** - Consistent naming throughout
- **Don't hardcode URLs** - Use server variables