OpenAI Codex & Cookbook — Official Collection

What it is

This collection bundles two official OpenAI resources. The first is Codex, OpenAI's CLI-based coding agent that reads your codebase, proposes changes, and executes them in a sandboxed environment. The second is the OpenAI Cookbook, a repository of practical guides and examples for working with GPT models, the Realtime API, embeddings, and function calling.

These resources target developers who use OpenAI APIs and want reference implementations, prompt engineering patterns, and a coding agent that integrates directly into terminal workflows.

How it saves time or tokens

The Cookbook provides tested prompt templates and code snippets that you can copy directly into your projects. Instead of experimenting with prompt formats from scratch, you start from working examples that OpenAI engineers have validated. This reduces trial-and-error token usage during prompt development.

Codex CLI acts as a coding agent in your terminal. It reads relevant files, generates diffs, and applies changes after your approval. This keeps you in the terminal without switching to a browser-based chat interface.

How to use

1. Install Codex CLI: npm install -g @openai/codex. Set your OPENAI_API_KEY environment variable.
2. Run codex in your project directory. Describe what you want to change in natural language. Codex reads your codebase, generates a plan, and shows you the proposed diff.
3. For the Cookbook, browse the GitHub repository or the docs site. Each guide is a standalone Jupyter notebook or Python script covering a specific use case.

Example

# Using Codex CLI to add error handling
$ codex 'Add retry logic with exponential backoff to the API client in src/api.ts'

# Codex reads src/api.ts, generates a diff:
# + import { retry } from './utils/retry';
# + const response = await retry(() => fetch(url), { maxRetries: 3 });

# You review and approve the changes

Codex operates in a sandbox by default, so it cannot make destructive changes without your explicit approval.

Related on TokRepo

• AI tools for coding — Compare AI coding assistants and agents
• Prompt library — Curated prompt templates for various AI models

Common pitfalls

• Codex CLI requires an OpenAI API key with access to the latest models. Costs depend on which model you configure and how much context your codebase requires.
• Cookbook examples target specific API versions. Some older notebooks may reference deprecated endpoints. Always check the last-updated date on each guide.
• Codex sandbox mode restricts file system and network access. If you need the agent to run tests or install packages, you must explicitly grant those permissions.