Demo How to Use Claude API

!pip install anthropic

# python
import os
import anthropic

# Prefer environment variable; replace with a secure source in real projects.
CLAUDE_API_KEY = os.environ.get("CLAUDE_API_KEY", "<YOUR_CLAUDE_API_KEY>")

# Initialize client
# Depending on the SDK version this may be `anthropic.Client(...)` or `anthropic.Anthropic(...)`.
client = anthropic.Anthropic(api_key=CLAUDE_API_KEY)

# System prompt defines the assistant's role/personality.
system_prompt = "You are a helpful research assistant. Answer clearly and concisely."

# Short-term chat history (list of {"role": "user" | "assistant", "content": str})
message_history = []

def run_claude_agent(message_history, user_input):
    """
    Append the user input to the message history, send the conversation
    (with system prompt) to Claude, append the assistant reply to history,
    and return the assistant reply.
    """
    # Add user message to history
    message_history.append({"role": "user", "content": user_input})

    # Send request to Claude
    response = client.messages.create(
        model="claude-3-opus-20240229",
        max_tokens=500,
        temperature=0.7,
        system=system_prompt,        # Some SDKs take system separately; follow your SDK docs
        messages=message_history     # messages should use "user" and "assistant" roles
    )

    # Extract assistant text from response.
    # SDK response formats vary between versions; try common patterns.
    assistant_reply = ""
    if hasattr(response, "content") and len(response.content) > 0:
        first = response.content[0]
        # Some SDKs return objects with a 'text' attribute or dicts with 'text'
        assistant_reply = getattr(first, "text", None) or (first.get("text", "") if isinstance(first, dict) else str(first))
    else:
        # Fallback: represent the raw response
        assistant_reply = str(response)

    # Add assistant reply to history and return
    message_history.append({"role": "assistant", "content": assistant_reply})
    return assistant_reply

# Interactive chat loop
if __name__ == "__main__":
    print("Start chatting with the Claude agent. Type 'exit' or 'quit' to end.")
    while True:
        user_input = input("You: ").strip()
        if user_input.lower() in ["exit", "quit"]:
            print("Exiting Claude agent, goodbye!")
            break

        reply = run_claude_agent(message_history, user_input)
        print("\nClaude:", reply, "\n")