Add phone, SMS, and email tools to a LangGraph agent

1. Install

The Hail Python SDK needs Python 3.11+.

pip install hail-sdk
# .env
HAIL_API_KEY="hl_live_9fa2..."
pip install langgraph langchain

2. Define the tools

Each tool makes one SDK call. Every send must set recipient_consent. The API refuses a send without it.

from langchain_core.tools import tool
from hail import Client

@tool
async def send_sms(to: str, body: str) -> str:
    """Text an opted-in recipient."""
    async with Client() as hail:  # reads HAIL_API_KEY
        sms = await hail.sms.create(
            to=to, body=body, recipient_consent=True,
        )
        return f"queued {sms['id']}"

@tool
async def send_email(to: str, subject: str, body_text: str) -> str:
    """Email a recipient from your Hail inbox."""
    async with Client() as hail:
        msg = await hail.emails.create(
            to=[to], subject=subject,
            body_text=body_text, recipient_consent=True,
        )
        return f"queued {msg['id']}"

3. Add the tools to the graph

The prebuilt ReAct agent selects the tool for the task. Calls work the same way with hail.calls.create.

from langgraph.prebuilt import create_react_agent

agent = create_react_agent(
    "anthropic:claude-sonnet-5",
    tools=[send_sms, send_email],
)
result = await agent.ainvoke(
    {"messages": [("user", "Text +14155550142 that order 4471 shipped")]}
)

4. Receive replies

Hail sends inbound SMS and email to your webhook or to the event stream. The graph can then continue with the reply.

async with Client() as hail:
    async for ev in hail.events.tail():
        if ev["type"] == "sms.received":
            # feed the reply back into the graph
            handle(ev)

Questions

Run the examples

The examples above run as written with a Hail account and an API key. You pay for usage.