Anthropic Claude SDK

import anthropic
 
client = anthropic.Anthropic()
message = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=1024,
    system="You are a helpful assistant.",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(message.content[0].text)

"""anthropic_claude_sdk.py - messages, streaming, and tool use."""
from __future__ import annotations
 
import json
import anthropic
 
client = anthropic.Anthropic()
 
# Basic message
response = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=512,
    system="You are a Python code reviewer. Be concise.",
    messages=[{"role": "user", "content": "Review: def add(a,b): return a+b"}],
)
print(response.content[0].text)
 
# Streaming
print("--- streaming ---")
with client.messages.stream(
    model="claude-sonnet-4-20250514",
    max_tokens=256,
    messages=[{"role": "user", "content": "Count from 1 to 5."}],
) as stream:
    for text in stream.text_stream:
        print(text, end="", flush=True)
print()
 
# Tool use
tools = [{
    "name": "get_weather",
    "description": "Get weather for a city",
    "input_schema": {
        "type": "object",
        "properties": {"city": {"type": "string"}},
        "required": ["city"],
    },
}]
 
def get_weather(city: str) -> str:
    return json.dumps({"city": city, "temp_f": 72, "condition": "sunny"})
 
msg = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=1024,
    tools=tools,
    messages=[{"role": "user", "content": "What's the weather in Austin?"}],
)
 
while msg.stop_reason == "tool_use":
    tool_results = []
    for block in msg.content:
        if block.type == "tool_use":
            result = get_weather(**block.input)
            tool_results.append({
                "type": "tool_result",
                "tool_use_id": block.id,
                "content": result,
            })
    msg = client.messages.create(
        model="claude-sonnet-4-20250514",
        max_tokens=1024,
        tools=tools,
        messages=[
            {"role": "user", "content": "What's the weather in Austin?"},
            {"role": "assistant", "content": msg.content},
            {"role": "user", "content": tool_results},
        ],
    )
print(msg.content[0].text)

# Async client
import asyncio
import anthropic
 
async def main():
    client = anthropic.AsyncAnthropic()
    msg = await client.messages.create(
        model="claude-sonnet-4-20250514",
        max_tokens=256,
        messages=[{"role": "user", "content": "Hi"}],
    )
    print(msg.content[0].text)
 
asyncio.run(main())