API Docs Writer Skill

This skill transforms raw API specs, endpoint descriptions, or Postman collections into clean, developer-facing documentation following OpenAPI-adjacent conventions. Output is ready for a developer portal, README, or Notion/Confluence page.

Required Inputs

Ask the user for these if not provided:

• API or endpoint details (raw spec, Postman export, or verbal description)
• Auth method (API key / Bearer token / OAuth 2.0 / None)
• Base URL
• Audience (internal developers / external partners / public)
• Output format (Markdown / OpenAPI YAML / Plain prose)

Output Structure

For each endpoint, produce the following:

---

[METHOD] /path/to/endpoint

Summary: [One line — what this endpoint does]

Description: [2–4 sentences. When to use this endpoint. What it returns. Any important behaviour to know (pagination, rate limits, async processing, etc.)]

Authentication: [Required / Optional — method]

---

Request

Headers:

Header	Required	Description
Authorization	Yes	Bearer <token>
Content-Type	Yes	application/json

Path Parameters:

Parameter	Type	Required	Description
id	string	Yes	Unique identifier for the resource

Query Parameters:

Parameter	Type	Required	Default	Description
limit	integer	No	20	Max results per page (1–100)
cursor	string	No	—	Pagination cursor from previous response

Request Body:

{
  "field_name": "value",
  "another_field": 42
}

Field	Type	Required	Description
field_name	string	Yes	[Plain description of what this field does]
another_field	integer	No	[Description. Include valid range or enum values if applicable]

---

Response

Success Response: 200 OK

{
  "id": "abc123",
  "status": "active",
  "created_at": "2025-04-01T10:00:00Z"
}

Field	Type	Description
id	string	Unique identifier for the created/retrieved resource
status	string	Current status. Enum: active, inactive, pending
created_at	ISO 8601 string	Timestamp of creation in UTC

---

Error Codes

Status Code	Error Code	Description	How to Resolve
400	INVALID_REQUEST	Request body is malformed or missing required fields	Check request body against schema above
401	UNAUTHORIZED	Missing or invalid authentication token	Verify your API key or refresh your token
404	NOT_FOUND	The requested resource does not exist	Check the ID in the path parameter
429	RATE_LIMITED	Too many requests	Back off and retry after Retry-After header value
500	INTERNAL_ERROR	Unexpected server error	Retry with exponential backoff; contact support if persists

---

Code Examples

Produce examples in at least 2 languages relevant to the audience (default: cURL + Python):

cURL:

curl -X POST https://api.example.com/v1/endpoint \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"field_name": "value"}'

Python:

import requests

response = requests.post(
    "https://api.example.com/v1/endpoint",
    headers={"Authorization": "Bearer YOUR_TOKEN"},
    json={"field_name": "value"}
)
data = response.json()

---

Quality Checks

• Every parameter is documented (type, required/optional, description)
• Response fields are fully documented with types
• All relevant error codes are listed with resolution guidance
• Code examples are copy-paste runnable (no pseudocode)
• Auth method is clearly stated at the top
• Enum values are listed where applicable
• Pagination documented if the endpoint is a list endpoint

Example Trigger Phrases

• "Document this API endpoint: [paste spec or description]"
• "Turn this Postman collection into developer docs"
• "Write API reference docs for [endpoint]"
• "Write a developer guide for our [product] API"