Anthropic Install & Auth

Overview

Set up the Anthropic SDK and configure your API key to start using Claude models.

Prerequisites

Node.js 18+ or Python 3.10+
Anthropic account at console.anthropic.com
API key from Settings → API Keys (starts with sk-ant-)

Instructions

Step 1: Install SDK

# Node.js / TypeScript
npm install @claude-ai/sdk

# Python
pip install anthropic

Step 2: Configure API Key

# Set environment variable (recommended)
export ANTHROPIC_API_KEY="sk-ant-api03-..."

# Or add to .env file
echo 'ANTHROPIC_API_KEY=sk-ant-api03-...' >> .env

Important: Never hardcode API keys. Use environment variables or a secrets manager. Keys start with sk-ant-.

Step 3: Verify Connection

import Anthropic from '@claude-ai/sdk';

const client = new Anthropic(); // reads ANTHROPIC_API_KEY from env

const message = await client.messages.create({
  model: 'claude-sonnet-4-20250514',
  max_tokens: 64,
  messages: [{ role: 'user', content: 'Say "connected" in one word.' }],
});
console.log(message.content[0].text); // "Connected"

import anthropic

client = anthropic.Anthropic()  # reads ANTHROPIC_API_KEY from env

message = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=64,
    messages=[{"role": "user", "content": "Say 'connected' in one word."}],
)
print(message.content[0].text)  # "Connected"

Output

@claude-ai/sdk in node_modules or anthropic in site-packages
ANTHROPIC_API_KEY environment variable set
Successful Claude response confirming API access

Error Handling

Error	Cause	Solution
`authentication_error` (401)	API key missing, invalid, or revoked	Check key at console.anthropic.com → API Keys
`permission_error` (403)	Key lacks access to requested model	Verify workspace has model access enabled
`ModuleNotFoundError`	SDK not installed	`pip install anthropic` or `npm i @claude-ai/sdk`
`Could not resolve host`	Network/DNS issue	Check internet connectivity and proxy settings

Examples

TypeScript Setup

import Anthropic from '@claude-ai/sdk';

// Default: reads ANTHROPIC_API_KEY from environment
const client = new Anthropic();

// Explicit key (for testing only — don't hardcode in production)
const client = new Anthropic({ apiKey: 'sk-ant-api03-...' });

// Custom base URL (for proxies or Vertex AI)
const client = new Anthropic({
  baseURL: 'https://your-proxy.example.com',
});

Python Setup

import anthropic

# Default: reads ANTHROPIC_API_KEY from environment
client = anthropic.Anthropic()

# Explicit key
client = anthropic.Anthropic(api_key="sk-ant-api03-...")

# Async client
client = anthropic.AsyncAnthropic()

Resources

Next Steps

After successful auth, proceed to clade-hello-world for your first Claude conversation.