Step 2: Project Setup — Build Your Own AI CLI Tool

One-Line Summary: Initialize the Node.js project, install all dependencies, configure TypeScript, and wire up the bin entry so the CLI runs as a global command.

Prerequisites: Node.js 18+ installed, npm, an Anthropic API key

Create the Project

mkdir ask-cli && cd ask-cli
npm init -y

Install Dependencies

npm install commander @anthropic-ai/sdk chalk ora
npm install -D typescript @types/node

What each package does:

Package	Purpose
`commander`	CLI framework — parses arguments, subcommands, flags, and generates help text
`@anthropic-ai/sdk`	Official Anthropic TypeScript SDK — handles auth, requests, and streaming
`chalk`	Terminal string styling — colors, bold, dim text for readable output
`ora`	Elegant terminal spinners — visual feedback while waiting for API responses
`typescript`	TypeScript compiler

Configure TypeScript

Create tsconfig.json:

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "Node16",
    "moduleResolution": "Node16",
    "outDir": "./dist",
    "rootDir": "./src",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "declaration": true
  },
  "include": ["src/**/*"]
}

Update package.json

Open package.json and update it with these fields:

{
  "name": "ask-cli",
  "version": "1.0.0",
  "type": "commonjs",
  "bin": {
    "ask": "./dist/index.js"
  },
  "scripts": {
    "build": "tsc",
    "dev": "tsc --watch",
    "start": "node dist/index.js"
  }
}

The bin field is important — it tells npm to create an executable called ask that points to your compiled entry file. This is what makes ask "question" work from anywhere in your terminal after linking.

Set Your API Key

The Anthropic SDK reads your key from the ANTHROPIC_API_KEY environment variable. Add it to your shell profile:

# Add to ~/.bashrc, ~/.zshrc, or ~/.bash_profile
export ANTHROPIC_API_KEY="sk-ant-your-key-here"

Reload your shell:

source ~/.zshrc  # or ~/.bashrc

Create the Source Directory and Entry Point

mkdir src

Create the entry point at src/index.ts with a minimal shell to verify everything works:

#!/usr/bin/env node
// src/index.ts
// ------------------------------------------
// CLI Entry Point — verifies setup works
// ------------------------------------------
 
import { Command } from 'commander';
 
const program = new Command();
 
program
  .name('ask')
  .description('AI-powered terminal assistant')
  .version('1.0.0');
 
program.parse();

The #!/usr/bin/env node shebang is required — it tells the OS to run this file with Node.js when invoked as a CLI command.

Verify the Setup

npx tsc && node dist/index.js --help

You should see:

Usage: ask [options]
 
AI-powered terminal assistant
 
Options:
  -V, --version  output the version number
  -h, --help     display help for command

If that prints, your project is wired up correctly.

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