How to integrate Lemlist MCP with LangChain

This guide walks you through connecting Lemlist to LangChain using the Composio tool router. By the end, you'll have a working Lemlist agent that can export all leads from current campaign, download list of unsubscribed emails, unsubscribe specific lead from a campaign through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Lemlist account through Composio's Lemlist MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

Get started for free Get a demo

Lemlist

Api Key

Lemlist is a multichannel prospecting platform for outreach via email, LinkedIn, and calls. It streamlines lead generation and boosts reply rates with personalized, automated workflows.

54 Tools

Managed auth

Connect Lemlist without auth hassles

We manage OAuth, API keys, token refresh, and scopes — you just build.

Try for free

Introduction

This guide will help you understand how to give your LangChain agent real control over a Lemlist account through Composio's Lemlist MCP server.

Before we dive in, let's take a quick look at the key ideas and tools involved.

Also integrate Lemlist with

OpenAI Agents SDK Claude Agent SDK Claude Code Claude Cowork Codex OpenClaw Hermes CLI Google ADK Vercel AI SDK Mastra AI LlamaIndex CrewAI

TL;DR

Here's what you'll learn:

Get and set up your OpenAI and Composio API keys
Connect your Lemlist project to Composio
Create a Tool Router MCP session for Lemlist
Initialize an MCP client and retrieve Lemlist tools
Build a LangChain agent that can interact with Lemlist
Set up an interactive chat interface for testing

What is LangChain?

LangChain is a framework for developing applications powered by language models. It provides tools and abstractions for building agents that can reason, use tools, and maintain conversation context.

Key features include:

Agent Framework: Build agents that can use tools and make decisions
MCP Integration: Connect to external services through Model Context Protocol adapters
Memory Management: Maintain conversation history across interactions
Multi-Provider Support: Works with OpenAI, Anthropic, and other LLM providers

What is the Lemlist MCP server, and what's possible with it?

The Lemlist MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Lemlist account. It provides structured and secure access to your outreach campaigns, so your agent can manage leads, automate campaign exports, monitor unsubscribe lists, and orchestrate multichannel engagement on your behalf.

Automated campaign management: Retrieve campaign details by ID, audit campaign sequences, and start or monitor campaign exports for streamlined reporting and analytics.
Lead and subscriber control: Unsubscribe leads from campaigns, delete unsubscribed emails, or export detailed lists of campaign leads to keep your outreach data fresh and compliant.
Outreach data exports: Initiate and track asynchronous exports of campaign statistics or download CSVs of unsubscribed contacts for deeper insights and record-keeping.
Webhook administration: Fetch all configured webhooks to sync Lemlist with your other tools or audit integration points for better workflow automation.
Schedule management: Permanently delete schedules you no longer need, ensuring your campaigns stay organized and up to date.

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

Composio's Composio SDK helps agents find the right tools for a task at runtime. You can plug in multiple toolkits (like Gmail, HubSpot, and GitHub), and the agent will identify the relevant app and action to complete multi-step workflows. This can reduce token usage and improve the reliability of tool calls. Read more here: Getting started with Composio SDK

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Composio SDK works

The Composio SDK follows a three-phase workflow:

Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Step by step10 STEPS

Prerequisites

Before starting this tutorial, make sure you have:

Python 3.10 or higher installed on your system
A Composio account with an API key
An OpenAI API key
Basic familiarity with Python and async programming

Getting API Keys for OpenAI and Composio

OpenAI API Key

Go to the OpenAI dashboard and create an API key. You'll need credits to use the models, or you can connect to another model provider.
Keep the API key safe.

Composio API Key

Log in to the Composio dashboard.
Navigate to your API settings and generate a new API key.
Store this key securely as you'll need it for authentication.

Install dependencies

npm install @composio/langchain @langchain/core @langchain/openai @langchain/mcp-adapters dotenv

Install the required packages for LangChain with MCP support.

What's happening:

@composio/langchain provides Composio integration for LangChain
@langchain/mcp-adapters enables MCP client connections
@langchain/core is the core agent framework
dotenv/config loads environment variables

Set up environment variables

bash

COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_composio_user_id_here
OPENAI_API_KEY=your_openai_api_key_here

Create a .env file in your project root.

What's happening:

COMPOSIO_API_KEY authenticates your requests to Composio's API
COMPOSIO_USER_ID identifies the user for session management
OPENAI_API_KEY enables access to OpenAI's language models

Import dependencies

import { Composio } from '@composio/core';
import { LangchainProvider } from '@composio/langchain';
import { MultiServerMCPClient } from "@langchain/mcp-adapters";
import { createAgent } from "langchain";
import * as readline from 'readline';
import 'dotenv/config';

dotenv.config();

What's happening:

We're importing LangChain's MCP adapter and Composio SDK
The dotenv/config import loads environment variables from your .env file
This setup prepares the foundation for connecting LangChain with Lemlist functionality through MCP

Initialize Composio client

const composioApiKey = process.env.COMPOSIO_API_KEY;
const userId = process.env.COMPOSIO_USER_ID;

if (!composioApiKey) throw new Error('COMPOSIO_API_KEY is not set');
if (!userId) throw new Error('COMPOSIO_USER_ID is not set');

async function main() {
    const composio = new Composio({
        apiKey: composioApiKey as string,
        provider: new LangchainProvider()
    });

What's happening:

We're loading the COMPOSIO_API_KEY from environment variables and validating it exists
Creating a Composio instance that will manage our connection to Lemlist tools
Validating that COMPOSIO_USER_ID is also set before proceeding

Create a Tool Router session

const session = await composio.create(
    userId as string,
    {
        toolkits: ['lemlist']
    }
);

const url = session.mcp.url;

What's happening:

We're creating a Tool Router session that gives your agent access to Lemlist tools
The create method takes the user ID and specifies which toolkits should be available
The returned session.mcp.url is the MCP server URL that your agent will use
This approach allows the agent to dynamically load and use Lemlist tools as needed

Configure the agent with the MCP URL

const client = new MultiServerMCPClient({
    "lemlist-agent": {
        transport: "http",
        url: url,
        headers: {
            "x-api-key": process.env.COMPOSIO_API_KEY
        }
    }
});

const tools = await client.getTools();

const agent = createAgent({ model: "gpt-5", tools });

What's happening:

We're creating a MultiServerMCPClient that connects to our Lemlist MCP server via HTTP
The client is configured with a name and the URL from our Tool Router session
getTools() retrieves all available Lemlist tools that the agent can use
We're creating a LangChain agent using the GPT-5 model

Set up interactive chat interface

let conversationHistory: any[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
console.log("Ask any Lemlist related question or task to the agent.\n");

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: 'You: '
});

rl.prompt();

rl.on('line', async (userInput: string) => {
    const trimmedInput = userInput.trim();

    if (['exit', 'quit', 'bye'].includes(trimmedInput.toLowerCase())) {
        console.log("\nGoodbye!");
        rl.close();
        process.exit(0);
    }

    if (!trimmedInput) {
        rl.prompt();
        return;
    }

    conversationHistory.push({ role: "user", content: trimmedInput });
    console.log("\nAgent is thinking...\n");

    const response = await agent.invoke({ messages: conversationHistory });
    conversationHistory = response.messages;

    const finalResponse = response.messages[response.messages.length - 1]?.content;
    console.log(`Agent: ${finalResponse}\n`);
        
        rl.prompt();
    });

    rl.on('close', () => {
        console.log('\n👋 Session ended.');
        process.exit(0);
    });

What's happening:

We initialize an empty conversationHistory list to maintain context across interactions
A readline interface is used to continuously accept user input from the command line
When a user types a message, it's added to the conversation history and sent to the agent
The agent processes the request using the invoke() method with the full conversation history
Users can type 'exit', 'quit', or 'bye' to end the chat session gracefully

Run the application

main().catch((err) => {
    console.error('Fatal error:', err);
    process.exit(1);
});

What's happening:

We call the main() function to start the application

Complete Code

Here's the complete code to get you started with Lemlist and LangChain:

import { Composio } from '@composio/core';
import { LangchainProvider } from '@composio/langchain';
import { MultiServerMCPClient } from "@langchain/mcp-adapters";  
import { createAgent } from "langchain";
import * as readline from 'readline';
import 'dotenv/config';

const composioApiKey = process.env.COMPOSIO_API_KEY;
const userId = process.env.COMPOSIO_USER_ID;

if (!composioApiKey) throw new Error('COMPOSIO_API_KEY is not set');
if (!userId) throw new Error('COMPOSIO_USER_ID is not set');

async function main() {
    const composio = new Composio({
        apiKey: composioApiKey as string,
        provider: new LangchainProvider()
    });

    const session = await composio.create(
        userId as string,
        {
            toolkits: ['lemlist']
        }
    );

    const url = session.mcp.url;
    
    const client = new MultiServerMCPClient({
        "lemlist-agent": {
            transport: "http",
            url: url,
            headers: {
                "x-api-key": process.env.COMPOSIO_API_KEY
            }
        }
    });
    
    const tools = await client.getTools();
  
    const agent = createAgent({ model: "gpt-5", tools });
    
    let conversationHistory: any[] = [];
    
    console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
    console.log("Ask any Lemlist related question or task to the agent.\n");
    
    const rl = readline.createInterface({
        input: process.stdin,
        output: process.stdout,
        prompt: 'You: '
    });

    rl.prompt();

    rl.on('line', async (userInput: string) => {
        const trimmedInput = userInput.trim();
        
        if (['exit', 'quit', 'bye'].includes(trimmedInput.toLowerCase())) {
            console.log("\nGoodbye!");
            rl.close();
            process.exit(0);
        }
        
        if (!trimmedInput) {
            rl.prompt();
            return;
        }
        
        conversationHistory.push({ role: "user", content: trimmedInput });
        console.log("\nAgent is thinking...\n");
        
        const response = await agent.invoke({ messages: conversationHistory });
        conversationHistory = response.messages;
        
        const finalResponse = response.messages[response.messages.length - 1]?.content;
        console.log(`Agent: ${finalResponse}\n`);
        
        rl.prompt();
    });

    rl.on('close', () => {
        console.log('\nSession ended.');
        process.exit(0);
    });
}

main().catch((err) => {
    console.error('Fatal error:', err);
    process.exit(1);
});

Conclusion

You've successfully built a LangChain agent that can interact with Lemlist through Composio's Tool Router.

Key features of this implementation:

Dynamic tool loading through Composio's Tool Router
Conversation history maintenance for context-aware responses
Async Python provides clean, efficient execution of agent workflows

You can extend this further by adding error handling, implementing specific business logic, or integrating additional Composio toolkits to create multi-app workflows.

TOOLS

Supported Tools

Every Lemlist action and event your agent gets out of the box.

Create Company Note

Tool to create a note attached to a specific company.

Delete Schedule

Tool to delete a specific schedule by scheduleId.

Delete Unsubscribed Email

Tool to delete an email from the unsubscribed list.

Unsubscribe Lead From Campaign

Tool to unsubscribe a lead from a campaign.

Get All Webhooks

Tool to retrieve the list of all webhooks configured for the team.

Get Campaign By ID

Tool to retrieve a specific campaign by campaignId.

Start Campaign Export

Tool to start an asynchronous export of all campaign statistics (CSV).

Get Campaign Export Status

Tool to check the status of an asynchronous campaign export.

Get Campaign Sequences

Tool to retrieve a list of all sequences for a campaign with steps and conditions.

Get Campaign Stats

Tool to retrieve performance statistics for a specific campaign within a date range.

Get Companies Schema

Tool to retrieve the schema definition for companies in the people database.

Get Contact Messages

Tool to retrieve all messages exchanged with a specific contact.

Get Database Filters

Tool to retrieve available filters for searching the people and companies database.

Export Campaign Leads

Tool to export campaign leads with state filtering and choose between JSON or CSV output.

Export Unsubscribes

Tool to download a CSV file containing all unsubscribed email addresses.

Get Unsubscribed Email

Tool to retrieve a single unsubscribed email record.

Get Label

Tool to retrieve information about a specific label by its ID.

List Campaigns

Tool to retrieve a list of campaigns for the team.

List Tasks

Tool to retrieve all pending tasks assigned to team members.

List Team Senders

Tool to retrieve all team members and their associated campaigns.

List Watchlist Signals

Tool to retrieve paginated watchlist signals with filtering and sorting.

Get People Schema

Tool to retrieve the schema definition for people in the people database.

Retrieve Activities

Tool to fetch recent campaign activities.

Retrieve Lead By Email

Tool to retrieve a lead by their email address.

Retrieve Unsubscribes

Tool to retrieve the list of all people who are unsubscribed.

Get Team Credits

Tool to retrieve credits left in the team.

Get Team Info

Tool to retrieve information about your team.

Get User

Tool to retrieve all information for a specific user by their ID.

Get User Info

Tool to retrieve all information of the authenticated user.

List Companies

Tool to retrieve a paginated list of all companies in your CRM.

List Company Notes

Tool to retrieve all notes associated with a specific company.

List Labels

Tool to list all labels available to your team.

Mark Lead as Not Interested in Campaign

Tool to mark a lead as not interested in a specific campaign.

Update Campaign

Tool to update settings of a campaign.

Update Schedule

Tool to update an existing schedule with new parameters.

Update Sequence Step

Tool to update an existing step in a sequence (edit subject/message/delay/etc.

Add Step to Sequence

Tool to add a new step (email, LinkedIn, conditional, etc.

Add Unsubscribe Email/Domain

Tool to add an email or domain to the unsubscribed list.

Add Variables to Lead

Tool to add one or more variables to a lead.

Associate schedule with campaign

Tool to associate a schedule with a campaign.

Create Campaign

Tool to create a new campaign.

Create Label

Tool to create a new label for inbox conversations.

Create Lead In Campaign

Tool to create a lead and add it to a specific campaign.

Create Schedule

Tool to create a new schedule for the team.

Create Task

Tool to create a manual task (opportunity) associated with a contact, company, or lead.

Ignore Tasks

Tool to mark one or more tasks as ignored in Lemlist.

Mark Lead As Interested

Tool to mark a lead as interested in all campaigns.

Mark Lead As Interested In Campaign

Tool to mark a lead as interested in a specific campaign.

Mark Lead As Not Interested

Tool to mark a lead as not interested in all campaigns.

Pause a running campaign

Tool to pause a running campaign.

Pause Lead

Tool to pause a lead in all campaigns or a specific campaign.

Search Companies Database

Tool to search the companies database using filters, keywords, and pagination.

Search People Database

Tool to search the Lemlist people database using filters, keywords, and pagination.

Update Task

Tool to update an existing task including assignment, scheduling, and status.

FRAMEWORKS

How to build Lemlist MCP Agent with another framework

OpenAI Agents SDK

Use Lemlist MCP with OpenAI Agents SDK

Claude Agent SDK

Use Lemlist MCP with Claude Agent SDK

Claude Code

Use Lemlist MCP with Claude Code

Claude Cowork

Use Lemlist MCP with Claude Cowork

Codex

Use Lemlist MCP with Codex

OpenClaw

Use Lemlist MCP with OpenClaw

Hermes

Use Lemlist MCP with Hermes

CLI

Use Lemlist MCP with CLI

Google ADK

Use Lemlist MCP with Google ADK

Vercel AI SDK

Use Lemlist MCP with Vercel AI SDK

Mastra AI

Use Lemlist MCP with Mastra AI

LlamaIndex

Use Lemlist MCP with LlamaIndex

CrewAI

Use Lemlist MCP with CrewAI

MORE TOOLKITS

Explore Other Toolkits

Toolkit marketplace

Aeroleads

Api Key

Aeroleads is a B2B lead generation platform for finding business emails and phone numbers. Grow your sales pipeline faster with powerful prospecting tools.

Autobound

Api Key

Autobound is an AI-powered sales engagement platform that crafts hyper-personalized outreach and insights. It helps sales teams boost response rates and close more deals through tailored content and recommendations.

Better proposals

Api Key

Better Proposals is a web-based tool for crafting and sending professional proposals. It helps teams impress clients and close deals faster with slick, easy-to-use templates.

Bidsketch

Api Key

Bidsketch is a proposal software that helps businesses create professional proposals quickly and efficiently. It streamlines the proposal process, saving time while boosting client win rates.

FAQ

Frequently asked questions

With a standalone Lemlist MCP server, the agents and LLMs can only access a fixed set of Lemlist tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Lemlist and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. LangChain fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Lemlist tools.

Yes, absolutely. You can configure which Lemlist scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Lemlist data and credentials are handled as safely as possible.

Start with Lemlist.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Lemlist tool your agent needs.Free to start.

Start building

Customer stories

Teams ship real agents on Composio

GET STARTED FOR FREE BOOK A DEMO

Karan skipped his own birthday party to fix our critical issue. It was 10pm and he diverted his Waymo to help us instead. This really sets the bar — it shows the commitment you need when users rely on your software.

Harsha Gaddipati

Co-founder, Slashy

A lot of students tell us that the moment their connected tools start talking to each other inside Opennote feels almost magical. The agent just knows them, and it's immensely helped keep new users on the platform.

Abhi Arya

Co-founder, Opennote

We chose Composio over Pipedream because it delivered depth where it mattered — niche tools and tricky edge cases other platforms simply ignored. That gave us confidence to scale without compromising.

Nirman Dave

CEO, Zams

As a solo builder, shipping fast is life or death. The only way I can outcompete incumbents is by outmanoeuvring them. Getting bogged down managing agent auth would have been a death sentence.

Ryan Yu

Founder, Extra Thursday

Before Composio, adding tool integrations was slow and resource-intensive. Each one could take weeks of engineering time, and maintaining them meant constantly keeping up with API changes.

Tomisin Jenrola

Founder & CEO, SwarmZero

With hands-on help from their founder, we integrated Gmail and Google Drive in just 30 minutes. This level of personal support and commitment is exactly what startups should strive for.

Jerome Leclanche

Co-Founder, Ingram Technologies

How to integrate Lemlist MCP with LangChain

Connect Lemlist without auth hassles

Introduction

Also integrate Lemlist with

TL;DR

What is LangChain?

What is the Lemlist MCP server, and what's possible with it?

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

How the Composio SDK works

Step-by-step Guide

Prerequisites

Getting API Keys for OpenAI and Composio

Install dependencies

Set up environment variables

Import dependencies

Initialize Composio client

Create a Tool Router session

Configure the agent with the MCP URL

Set up interactive chat interface

Run the application

Complete Code

Conclusion

Supported Tools

How to build Lemlist MCP Agent with another framework

OpenAI Agents SDK

Claude Agent SDK

Claude Code

Claude Cowork

Codex

OpenClaw

Hermes

CLI

Google ADK

Vercel AI SDK

Mastra AI

LlamaIndex

CrewAI

Explore Other Toolkits

Aeroleads

Autobound

Better proposals

Bidsketch

Frequently asked questions

What are the differences in Tool Router MCP and Lemlist MCP?+

Can I use Tool Router MCP with LangChain?+

Can I manage the permissions and scopes for Lemlist while using Tool Router?+

How safe is my data with Composio Tool Router?+

Start with Lemlist.It takes 30 seconds.

Teams ship real agents on Composio