Generate and maintain OpenAPI 3.1 specifications from code

Openapi spec generation

by wshobson · MIT license · ★ 39,857 on GitHub · updated Sep 21

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.

---
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

Overview

Comprehensive patterns for creating, maintaining, and validating OpenAPI 3.1 specifications for RESTful APIs.

Manual install (npx, ZIP)

Claude Codenpx skills add wshobson/agents --skill openapi-spec-generation -g -a claude-code

Claude Code (manual)

mkdir -p ~/.claude/skills && curl -sL https://codeload.github.com/wshobson/agents/tar.gz/4236bb91f839 \
  | tar -xz -C ~/.claude/skills --strip-components=4 agents-4236bb91f839/plugins/documentation-generation/skills/openapi-spec-generation

Windows (PowerShell)

New-Item -ItemType Directory -Force "$HOME\.claude\skills" | Out-Null; Invoke-WebRequest "https://m.agentalley.io/zip/fc42a797c3e4a3b393f3/openapi-spec-generation.zip" -OutFile "$env:TEMP\openapi-spec-generation.zip"; Expand-Archive "$env:TEMP\openapi-spec-generation.zip" -DestinationPath "$HOME\.claude\skills" -Force

Claude.ai / desktopDownload the ZIP and upload it under Settings → Capabilities → Skills.

Codex, Cursor, other agentsPoint them at SKILL.md. The other files are plain text.

Connects with Agent Alley MCP · agentalley.io/mcp

Files included

SKILL.md2.0 KB
references/2 files · 23.1 KB

Read the files here

wshobson/4236bb93 files

SKILL.md2.0 KB

SKILL.md

Show the full text67 lines

openapi-spec-generation/SKILL.md67 lines · 2.0 KB

PreviewCode

Outline

RawView on GitHub

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

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

1	---
2	name: openapi-spec-generation
3	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.
4	---
5
6	# OpenAPI Spec Generation
7
8	Comprehensive patterns for creating, maintaining, and validating OpenAPI 3.1 specifications for RESTful APIs.
9
10	## When to Use This Skill
11
12	- Creating API documentation from scratch
13	- Generating OpenAPI specs from existing code
14	- Designing API contracts (design-first approach)
15	- Validating API implementations against specs
16	- Generating client SDKs from specs
17	- Setting up API documentation portals
18
19	## Core Concepts
20
21	### 1. OpenAPI 3.1 Structure
22
23	```yaml
24	openapi: 3.1.0
25	info:
26	title: API Title
27	version: 1.0.0
28	servers:
29	- url: https://api.example.com/v1
30	paths:
31	/resources:
32	get: ...
33	components:
34	schemas: ...
35	securitySchemes: ...
36	```
37
38	### 2. Design Approaches
39
40	\| Approach \| Description \| Best For \|
41	\| ---------------- \| ---------------------------- \| ------------------- \|
42	\| Design-First \| Write spec before code \| New APIs, contracts \|
43	\| Code-First \| Generate spec from code \| Existing APIs \|
44	\| Hybrid \| Annotate code, generate spec \| Evolving APIs \|
45
46	## Templates and detailed worked examples
47
48	Full template library and detailed worked examples live in `references/details.md`. Read that file when you need the concrete templates.
49
50	## Best Practices
51
52	### Do's
53
54	- Use $ref - Reuse schemas, parameters, responses
55	- Add examples - Real-world values help consumers
56	- Document errors - All possible error codes
57	- Version your API - In URL or header
58	- Use semantic versioning - For spec changes
59
60	### Don'ts
61
62	- Don't use generic descriptions - Be specific
63	- Don't skip security - Define all schemes
64	- Don't forget nullable - Be explicit about null
65	- Don't mix styles - Consistent naming throughout
66	- Don't hardcode URLs - Use server variables
67