Migrating from DeepSeek to Anthropic: A Practical Guide

import os
from openai import OpenAI
client = OpenAI(api_key=os.environ["DEEPSEEK_API_KEY"], base_url="https://api.deepseek.com")

resp = client.chat.completions.create(
  model="deepseek-chat",
  messages=[
      {"role": "system", "content": "You are concise."},
      {"role": "user", "content": "Explain rate limits in one line."},
  ],
)
print(resp.choices[0].message.content)

import anthropic
client = anthropic.Anthropic()

resp = client.messages.create(
  model="claude-sonnet-4-6",
  max_tokens=1024,                       # now required
  system="You are concise.",             # lifted out of messages
  messages=[{"role": "user", "content": "Explain rate limits in one line."}],
)
print(resp.content[0].text)