How to integrate Lemlist MCP with Mastra AI

This guide walks you through connecting Lemlist to Mastra AI 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 Mastra AI 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.

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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

Introduction

This guide walks you through connecting Lemlist to Mastra AI 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 Mastra AI 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 SDKClaude Agent SDKClaude CodeClaude CoworkCodexOpenClawHermesCLIGoogle ADKLangChainVercel AI SDKLlamaIndexCrewAI

TL;DR

Here's what you'll learn:
  • Set up your environment so Mastra, OpenAI, and Composio work together
  • Create a Tool Router session in Composio that exposes Lemlist tools
  • Connect Mastra's MCP client to the Composio generated MCP URL
  • Fetch Lemlist tool definitions and attach them as a toolset
  • Build a Mastra agent that can reason, call tools, and return structured results
  • Run an interactive CLI where you can chat with your Lemlist agent

What is Mastra AI?

Mastra AI is a TypeScript framework for building AI agents with tool support. It provides a clean API for creating agents that can use external services through MCP.

Key features include:

  • MCP Client: Built-in support for Model Context Protocol servers
  • Toolsets: Organize tools into logical groups
  • Step Callbacks: Monitor and debug agent execution
  • OpenAI Integration: Works with OpenAI models via @ai-sdk/openai

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:

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

Step-by-step Guide

Step by step09 STEPS
1

Prerequisites

Before starting, make sure you have:
  • Node.js 18 or higher
  • A Composio account with an active API key
  • An OpenAI API key
  • Basic familiarity with TypeScript
2

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key.
  • You need credits or a connected billing setup to use the models.
  • Store the key somewhere safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Go to Settings and copy your API key.
  • This key lets your Mastra agent talk to Composio and reach Lemlist through MCP.
3

Install dependencies

bash
npm install @composio/core @mastra/core @mastra/mcp @ai-sdk/openai dotenv

Install the required packages.

What's happening:

  • @composio/core is the Composio SDK for creating MCP sessions
  • @mastra/core provides the Agent class
  • @mastra/mcp is Mastra's MCP client
  • @ai-sdk/openai is the model wrapper for OpenAI
  • dotenv loads environment variables from .env
4

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_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
  • COMPOSIO_USER_ID tells Composio which user this session belongs to
  • OPENAI_API_KEY lets the Mastra agent call OpenAI models
5

Import libraries and validate environment

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({
  apiKey: composioAPIKey as string,
});
What's happening:
  • dotenv/config auto loads your .env so process.env.* is available
  • openai gives you a Mastra compatible model wrapper
  • Agent is the Mastra agent that will call tools and produce answers
  • MCPClient connects Mastra to your Composio MCP server
  • Composio is used to create a Tool Router session
6

Create a Tool Router session for Lemlist

typescript
async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["lemlist"],
    },
  );

  const composioMCPUrl = session.mcp.url;
  console.log("Lemlist MCP URL:", composioMCPUrl);
What's happening:
  • create spins up a short-lived MCP HTTP endpoint for this user
  • The toolkits array contains "lemlist" for Lemlist access
  • session.mcp.url is the MCP URL that Mastra's MCPClient will connect to
7

Configure Mastra MCP client and fetch tools

typescript
const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      nasdaq: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

console.log("Fetching MCP tools from Composio...");
const composioTools = await mcpClient.getTools();
console.log("Number of tools:", Object.keys(composioTools).length);
What's happening:
  • MCPClient takes an id for this client and a list of MCP servers
  • The headers property includes the x-api-key for authentication
  • getTools fetches the tool definitions exposed by the Lemlist toolkit
8

Create the Mastra agent

typescript
const agent = new Agent({
    name: "lemlist-mastra-agent",
    instructions: "You are an AI agent with Lemlist tools via Composio.",
    model: "openai/gpt-5",
  });
What's happening:
  • Agent is the core Mastra agent
  • name is just an identifier for logging and debugging
  • instructions guide the agent to use tools instead of only answering in natural language
  • model uses openai("gpt-5") to configure the underlying LLM
9

Set up interactive chat interface

typescript
let messages: AiMessageType[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end.\n");

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

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;
  }

  messages.push({
    id: crypto.randomUUID(),
    role: "user",
    content: trimmedInput,
  });

  console.log("\nAgent is thinking...\n");

  try {
    const response = await agent.generate(messages, {
      toolsets: {
        lemlist: composioTools,
      },
      maxSteps: 8,
    });

    const { text } = response;

    if (text && text.trim().length > 0) {
      console.log(`Agent: ${text}\n`);
        messages.push({
          id: crypto.randomUUID(),
          role: "assistant",
          content: text,
        });
      }
    } catch (error) {
      console.error("\nError:", error);
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    console.log("\nSession ended.");
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(1);
});
What's happening:
  • messages keeps the full conversation history in Mastra's expected format
  • agent.generate runs the agent with conversation history and Lemlist toolsets
  • maxSteps limits how many tool calls the agent can take in a single run
  • onStepFinish is a hook that prints intermediate steps for debugging

Complete Code

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

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({ apiKey: composioAPIKey as string });

async function main() {
  const session = await composio.create(composioUserID as string, {
    toolkits: ["lemlist"],
  });

  const composioMCPUrl = session.mcp.url;

  const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      lemlist: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "lemlist-mastra-agent",
    instructions: "You are an AI agent with Lemlist tools via Composio.",
    model: "openai/gpt-5",
  });

  let messages: AiMessageType[] = [];

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

  rl.prompt();

  rl.on("line", async (input: string) => {
    const trimmed = input.trim();
    if (["exit", "quit"].includes(trimmed.toLowerCase())) {
      rl.close();
      return;
    }

    messages.push({ id: crypto.randomUUID(), role: "user", content: trimmed });

    const { text } = await agent.generate(messages, {
      toolsets: { lemlist: composioTools },
      maxSteps: 8,
    });

    if (text) {
      console.log(`Agent: ${text}\n`);
      messages.push({ id: crypto.randomUUID(), role: "assistant", content: text });
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main();

Conclusion

You've built a Mastra AI agent that can interact with Lemlist through Composio's Tool Router. You can extend this further by:
  • Adding other toolkits like Gmail, Slack, or GitHub
  • Building a web-based chat interface around this agent
  • Using multiple MCP endpoints to enable cross-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 logo

OpenAI Agents SDK

Use Lemlist MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Lemlist MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Lemlist MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Lemlist MCP with Claude Cowork

Codex logo

Codex

Use Lemlist MCP with Codex

OpenClaw logo

OpenClaw

Use Lemlist MCP with OpenClaw

Hermes logo

Hermes

Use Lemlist MCP with Hermes

CLI logo

CLI

Use Lemlist MCP with CLI

Google ADK logo

Google ADK

Use Lemlist MCP with Google ADK

LangChain logo

LangChain

Use Lemlist MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Lemlist MCP with Vercel AI SDK

LlamaIndex logo

LlamaIndex

Use Lemlist MCP with LlamaIndex

CrewAI logo

CrewAI

Use Lemlist MCP with CrewAI

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. Mastra AI 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.

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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.

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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.

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