Production email tool calling for LangChain agents with built-in security guardrails

import os
from langchain.tools import tool
from sadasend import SadaSend

client = SadaSend(api_key=os.environ["SADASEND_API_KEY"])

@tool
def send_transactional_email(to: str, subject: str, html: str) -> str:
    """Send an authenticated transactional email to a customer.
    Args:
        to: Recipient email address
        subject: Email subject line
        html: Email body in HTML format
    """
    response = client.emails.send(
        from_email="assistant@yourdomain.com",
        to=to,
        subject=subject,
        html=html,
        tags=["langchain-agent"]
    )
    return f"Email dispatched successfully. Message ID: {response.id}"