Anthropic SDK Basics

What Is an SDK?

An SDK (Software Development Kit) is a library that makes it easy to use an API. With Anthropic's official SDK, the library takes care of constructing HTTP requests, attaching authentication headers, handling errors, and managing retries on your behalf.

Official SDKs are provided for two languages — Python and TypeScript / JavaScript — and both are maintained by Anthropic source.

Installation

# Python
pip install anthropic

# TypeScript / JavaScript (Node.js)
npm install @anthropic-ai/sdk

Python — Minimal Code Example

The following is a minimal configuration based on the official documentation's code example source.

from anthropic import Anthropic

client = Anthropic()  # Automatically reads the ANTHROPIC_API_KEY environment variable

message = client.messages.create(
    model="claude-opus-4-7",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "こんにちは、Claude!"}
    ]
)

print(message.content[0].text)

TypeScript — Minimal Code Example

The following is a minimal configuration using TypeScript (ES Modules) source.

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic();  // Automatically reads the ANTHROPIC_API_KEY environment variable

const message = await client.messages.create({
  model: "claude-opus-4-7",
  max_tokens: 1024,
  messages: [
    { role: "user", content: "こんにちは、Claude!" }
  ]
});

console.log(message.content);

Response Structure

The Message object returned by messages.create() contains the following main fields.

• content — An array of text generation results. Normally, retrieve the body text via content[0].text.
• model — The name of the model that was used.
• stop_reason — The reason generation stopped ("end_turn" / "max_tokens" / "tool_use", etc.).
• usage — The number of input and output tokens. Used for cost calculation.

Required Parameters Explained

Detailed Article

For the full setup flow and practical examples, see "Getting Started with the Claude API — Python / TypeScript Examples in 5 Minutes".