Best Claude Code Prompt for “Write API Documentation

Claude Code is an agentic CLI that autonomously reads files, runs commands, and writes code. The single most important technique is verification-first prompting: start with what 'done' looks like (run tests, verify build) and describe outcomes, not implementation steps. This free template is optimized specifically for Claude Code, achieving approximately 37% token reduction compared to unoptimized prompts while producing higher quality output.

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What Most People Type

Write API documentation for my REST endpoint

Optimized Claude Code Prompt

<verification>
Run the test suite and ensure all tests pass.
Verify that the generated documentation accurately reflects the API endpoint's request and response structures.
Test that the API returns 200 for valid requests and 401 for unauthorized ones.
</verification>
<outcome>
Generate comprehensive API documentation for the provided REST endpoint. This documentation should detail the endpoint's purpose, request parameters (including types, required status, and descriptions), expected request body structure, and possible response codes with corresponding descriptions and body structures.
</outcome>
<context>
Refer to the existing documentation in the `docs/api` directory for style and formatting conventions.
Examine the controller file for the endpoint to understand its current implementation and data handling.
Pay close attention to the request validation and authentication middleware to accurately document their behavior.
</context>
<constraints>
Do not alter the existing API endpoint's functionality or behavior.
Adhere strictly to the OpenAPI Specification (OAS) v3.0 format for the documentation.
Ensure backward compatibility with existing API consumers.
The documentation should be clear, concise, and easy for developers to understand.
</constraints>
<git>
Create a new branch for these changes.
Commit the generated documentation files with a descriptive commit message.
</git>

Why This Claude Code Prompt for “Write API Documentation” Works Better

When you type “Write API documentation for my REST endpoint” into Claude Code, it lacks structure — Claude Code has to guess what format you want, how detailed to go, and what to prioritize. The optimized version removes that guesswork.

It starts with verification criteria (what 'done' looks like), describes the desired outcome rather than implementation steps, and scopes the task to specific files — matching Claude Code's agentic workflow.

This Prompt Optimized for Other AI Models

Each AI model processes instructions differently. See how this same prompt is optimized for:

Frequently Asked Questions

What makes a good Claude Code prompt for write api documentation?

Claude Code is an agentic CLI that autonomously reads files, runs commands, and writes code. The single most important technique is verification-first prompting: start with what 'done' looks like (run tests, verify build) and describe outcomes, not implementation steps.

Can I use this prompt template for free?

Yes — copy the optimized prompt below and paste it directly into Claude Code. For unlimited prompt optimization across all 5 AI models, try PromptOptimizr free with 10 prompts per month. You can also use the Chrome extension to optimize prompts directly inside your AI chat.

Why is this prompt different from a generic one?

Each AI model processes instructions differently. Claude Code has specific formatting preferences — this prompt is structured to work with those preferences, not against them. The result is better output quality with approximately 37% fewer tokens.

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