Give Your LangChain Agents Email Superpowers

import requests
from langchain.tools import tool

MULTIMAIL_API = "https://api.multimail.dev/v1"
HEADERS = {"Authorization": "Bearer mm_live_your_api_key"}

@tool
def send_email(to: str, subject: str, body: str, mailbox_id: str) -> str:
    """Send an email through MultiMail. In gated_send mode, this creates a pending draft for human approval."""
    resp = requests.post(f"{MULTIMAIL_API}/send", headers=HEADERS, json={
        "mailbox_id": mailbox_id,
        "to": to,
        "subject": subject,
        "body": body
    })
    return resp.json()

@tool
def check_inbox(mailbox_id: str, limit: int = 10) -> str:
    """Check the inbox for a given mailbox. Returns recent messages."""
    resp = requests.get(
        f"{MULTIMAIL_API}/mailboxes/{mailbox_id}/inbox",
        headers=HEADERS,
        params={"limit": limit}
    )
    return resp.json()

from langchain_openai import ChatOpenAI
from langchain.agents import create_tool_calling_agent, AgentExecutor
from langchain_core.prompts import ChatPromptTemplate

llm = ChatOpenAI(model="gpt-4o")
tools = [send_email, check_inbox]

prompt = ChatPromptTemplate.from_messages([
    ("system", "You are an email assistant. Use the provided tools to "
     "send and read emails. The mailbox is in gated_send mode, so "
     "sent emails will be queued for human approval before delivery."),
    ("human", "{input}"),
    ("placeholder", "{agent_scratchpad}")
])

agent = create_tool_calling_agent(llm, tools, prompt)
executor = AgentExecutor(agent=agent, tools=tools, verbose=True)

result = executor.invoke({
    "input": "Check my inbox and summarize any unread messages"
})

@tool
def reply_email(message_id: str, body: str) -> str:
    """Reply to an email by message ID. Maintains the thread context."""
    resp = requests.post(f"{MULTIMAIL_API}/reply", headers=HEADERS, json={
        "message_id": message_id,
        "body": body
    })
    return resp.json()

@tool
def get_thread(thread_id: str) -> str:
    """Get all messages in an email thread for context."""
    resp = requests.get(
        f"{MULTIMAIL_API}/threads/{thread_id}",
        headers=HEADERS
    )
    return resp.json()

"cm"># Add to your agent's tool list
tools = [send_email, check_inbox, reply_email, get_thread]

from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain.agents import create_tool_calling_agent, AgentExecutor

async def create_email_agent():
    async with MultiServerMCPClient({
        "multimail": {
            "command": "npx",
            "args": ["-y", "@multimail/mcp-server"],
            "env": {"MULTIMAIL_API_KEY": "mm_live_your_api_key"}
        }
    }) as client:
        tools = client.get_tools()  "cm"># Auto-discovers all MultiMail tools
        agent = create_tool_calling_agent(llm, tools, prompt)
        executor = AgentExecutor(agent=agent, tools=tools)
        result = await executor.ainvoke({
            "input": "Send a follow-up email to the last thread"
        })
        return result