How to integrate Mailerlite MCP with Claude Agent SDK

This guide walks you through connecting Mailerlite to the Claude Agent SDK using the Composio tool router. By the end, you'll have a working Mailerlite agent that can create a new subscriber group called vip customers, add a custom field for subscriber birthday, create a segment for recent e-commerce buyers through natural language commands. This guide will help you understand how to give your Claude Agent SDK agent real control over a Mailerlite account through Composio's Mailerlite MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Mailerlite

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MailerLite is an email marketing service for building, sending, and automating campaigns. It helps businesses reach audiences with beautiful emails, landing pages, and advanced automation.

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Introduction

This guide will help you understand how to give your Claude Agent SDK agent real control over a Mailerlite account through Composio's Mailerlite MCP server.

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

Also integrate Mailerlite with

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

TL;DR

Here's what you'll learn:

Get and set up your Claude/Anthropic and Composio API keys
Install the necessary dependencies
Initialize Composio and create a Tool Router session for Mailerlite
Configure an AI agent that can use Mailerlite as a tool
Run a live chat session where you can ask the agent to perform Mailerlite operations

What is Claude Agent SDK?

The Claude Agent SDK is Anthropic's official framework for building AI agents powered by Claude. It provides a streamlined interface for creating agents with MCP tool support and conversation management.

Key features include:

Native MCP Support: Built-in support for Model Context Protocol servers
Permission Modes: Control tool execution permissions
Streaming Responses: Real-time response streaming for interactive applications
Context Manager: Clean async context management for sessions

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

The Mailerlite MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Mailerlite account. It provides structured and secure access to your email marketing tools, so your agent can create campaigns, manage subscribers, automate workflows, and oversee your shop integrations with ease.

Campaign automation and workflow management: Instruct your agent to create or delete automations, streamlining your email marketing processes and ensuring timely communication with your audience.
E-commerce customer and shop integration: Let your agent create, update, or remove e-commerce customers and shops for seamless sales tracking, customer onboarding, or data syncing.
Subscriber group and segment organization: Have your agent create custom fields, new subscriber groups, or targeted segments so you can send highly personalized campaigns.
Webhook registration for real-time updates: Direct your agent to set up webhooks for specific events, enabling instant notifications and integrations with other systems as actions happen in Mailerlite.
Efficient cleanup and management: Ask your agent to delete outdated automations, customers, or shops, helping you keep your Mailerlite workspace 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 step09 STEPS

Prerequisites

Before starting, make sure you have:

Composio API Key and Claude/Anthropic API Key
Primary know-how of Claude Agents SDK
A Mailerlite account
Some knowledge of Python

Getting API Keys for Claude/Anthropic and Composio

Claude/Anthropic API Key

Go to the Anthropic Console and create an API key. You'll need credits to use the models.
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 @anthropic-ai/claude-agent-sdk @composio/core dotenv

Install the Composio SDK and the Claude Agents SDK.

What's happening:

@composio/core provides Composio integration for Anthropic
@anthropic-ai/claude-agent-sdk is the core agent framework
dotenv/config loads environment variables

Set up environment variables

bash

COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here
ANTHROPIC_API_KEY=your_anthropic_api_key_here

Create a .env file in your project root.

What's happening:

COMPOSIO_API_KEY authenticates with Composio
USER_ID identifies the user for session management
ANTHROPIC_API_KEY authenticates with Anthropic/Claude

Import dependencies

import 'dotenv/config';
import readline from 'node:readline';
import { Composio } from '@composio/core';
import { query, type Options } from "@anthropic-ai/claude-agent-sdk";

dotenv.config();

What's happening:

We're importing all necessary libraries including the Claude Agent SDK and Composio
The dotenv.config() function loads environment variables from your .env file
This setup prepares the foundation for connecting Claude with Mailerlite functionality

Create a Composio instance and Tool Router session

async function chat() {
  const { COMPOSIO_API_KEY, USER_ID } = process.env;
  if (!COMPOSIO_API_KEY || !USER_ID) {
    throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
  }

  const composio = new Composio({ apiKey: COMPOSIO_API_KEY });

  // Create Tool Router session for Mailerlite
  const session = await composio.create(USER_ID, {
    toolkits: ['mailerlite'],
  });
  const mcpUrl = session?.mcp.url;

What's happening:

The function checks for the required COMPOSIO_API_KEY environment variable
We're creating a Composio instance using our API key
The create method creates a Tool Router session for Mailerlite
The returned url is the MCP server URL that your agent will use

Configure Claude Agent with MCP

const options: Options = {
  permissionMode: 'bypassPermissions',
  mcpServers: {
    composio: {
      type: 'http',
      url: mcpUrl,
      headers: { 'x-api-key': COMPOSIO_API_KEY }
    }
  },
  systemPrompt: 'You are a helpful assistant with access to Mailerlite tools via Composio.',
  maxTurns: 10,
};

What's happening:

We're configuring the Claude Agent options with the MCP server URL
permissionMode: 'bypassPermissions' allows the agent to execute operations without asking for permission each time
The system prompt instructs the agent that it has access to Mailerlite
maxTurns: 10 limits the conversation length to prevent excessive API usage

Create client and start chat loop

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

  console.log('\nChat started. Type "exit" to quit.\n');

  let isProcessing = false;

  async function ask(prompt: string) {
    isProcessing = true;
    rl.pause();

    process.stdout.write('Claude is thinking...');
    const stream = query({ prompt, options });

    let firstChunk = true;
    for await (const msg of stream) {
      const content = (msg as any).message?.content || (msg as any).content;
      if (Array.isArray(content)) {
        for (const block of content) {
          if (block.type === 'text' && block.text) {
            if (firstChunk) {
              process.stdout.write('\r\x1b[K');
              process.stdout.write('Claude: ');
              firstChunk = false;
            }
            process.stdout.write(block.text);
          }
        }
      }
    }
    process.stdout.write('\n\n');

    isProcessing = false;
    rl.resume();
    rl.prompt();
  }

  rl.on('line', async (line) => {
    if (isProcessing) return;

    const input = line.trim();
    if (input === 'exit') {
      rl.close();
      process.exit(0);
    }
    if (input) await ask(input);
    else rl.prompt();
  });

  await ask('What can you help me with?');
}

What's happening:

The readline interface is created to handle user input and output
The query function is used to send the user's input to the agent
The chat loop continues until the user types 'exit' or 'quit'

Run the application

try {
  await chat();
} catch (error) {
  console.error(error);
  process.exit(1);
}

What's happening:

The chat function is the entry point for the application
The try-catch block is used to handle any errors that occur

Complete Code

Here's the complete code to get you started with Mailerlite and Claude Agent SDK:

import 'dotenv/config';
import readline from 'node:readline';
import { Composio } from '@composio/core';
import { query, type Options } from "@anthropic-ai/claude-agent-sdk";

async function chat() {
  const { COMPOSIO_API_KEY, USER_ID } = process.env;
  if (!COMPOSIO_API_KEY || !USER_ID) {
    throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
  }

  const composio = new Composio({ apiKey: COMPOSIO_API_KEY });
  const session = await composio.create(USER_ID, {
    toolkits: ['mailerlite']
  });
  const mcp_url = session?.mcp.url;

  const options: Options = {
    permissionMode: 'bypassPermissions',
    mcpServers: {
      composio: {
        type: 'http',
        url: mcp_url,
        headers: { 'x-api-key': COMPOSIO_API_KEY }
      }
    },
    systemPrompt: 'You are a helpful assistant with access to Mailerlite tools via Composio.',
    maxTurns: 10,
  };

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

  console.log('\nChat started. Type "exit" to quit.\n');

  let isProcessing = false;

  async function ask(prompt: string) {
    isProcessing = true;
    rl.pause();

    process.stdout.write('Claude is thinking...');
    const stream = query({ prompt, options });

    let firstChunk = true;
    for await (const msg of stream) {
      const content = (msg as any).message?.content || (msg as any).content;
      if (Array.isArray(content)) {
        for (const block of content) {
          if (block.type === 'text' && block.text) {
            if (firstChunk) {
              process.stdout.write('\r\x1b[K');
              process.stdout.write('Claude: ');
              firstChunk = false;
            }
            process.stdout.write(block.text);
          }
        }
      }
    }
    process.stdout.write('\n\n');

    isProcessing = false;
    rl.resume();
    rl.prompt();
  }

  rl.on('line', async (line) => {
    if (isProcessing) return;

    const input = line.trim();
    if (input === 'exit') {
      rl.close();
      process.exit(0);
    }
    if (input) await ask(input);
    else rl.prompt();
  });

  await ask('What can you help me with?');
}

try {
  await chat();
} catch (error) {
  console.error(error);
  process.exit(1);
}

Conclusion

You've successfully built a Claude Agent SDK agent that can interact with Mailerlite through Composio's Tool Router.

Key features:

Native MCP support through Claude's agent framework
Streaming responses for real-time interaction
Permission bypass for smooth automated workflows

You can extend this by adding more toolkits, implementing custom business logic, or building a web interface around the agent.

TOOLS

Supported Tools

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

Add Product to Category

Tool to add a product to a category in an e-commerce shop.

Add Subscriber To Group

Tool to assign an existing subscriber to a group.

Create automation

Create Campaign

Tool to create a new email campaign (draft) with specified type, content, and targeting.

Create E-commerce Cart Item

Tool to add an item to a shopping cart.

Create E-commerce Category

Tool to create a new product category for a shop.

Create/Update E-commerce Customer

Tool to create or update a customer record for a shop.

Create E-commerce Order

Tool to create a new order for a shop.

Create E-commerce Product

Tool to create a new product for an e-commerce shop.

Create E-commerce Shop

Tool to connect a new e-commerce shop.

Create Field

Tool to create a new custom field.

Create Group

Tool to create a new subscriber group.

Create Segment

Tool to create a new subscriber segment.

Create Subscriber

Tool to create or update (upsert) a subscriber by email.

Create Webhook

Tool to register a new webhook URL for specified event types.

Delete Automation

Tool to delete an automation workflow by ID.

Delete E-commerce Cart Item

Tool to remove an item from a cart in an e-commerce shop.

Delete E-commerce Category

Tool to delete a product category from an e-commerce shop by IDs.

Delete E-commerce Customer

Tool to delete a customer from an e-commerce shop by IDs.

Delete E-commerce Order

Tool to delete an order from a shop.

Delete E-commerce Product

Tool to delete a product from an e-commerce shop by IDs.

Delete E-commerce Shop

Tool to disconnect an e-commerce shop by ID.

Delete Field

Tool to delete a custom field.

Delete Group

Tool to delete a subscriber group by ID.

Delete Segment

Tool to delete a segment by ID.

Delete Subscriber

Tool to delete a subscriber by ID.

Delete Webhook

Tool to remove a webhook subscription by ID.

Execute Batch Request

Tool to execute multiple API requests in a single batch call (max 50 requests).

Forget Subscriber

Tool to forget a subscriber completely (GDPR compliant deletion).

Get Account Info

Tool to retrieve basic MailerLite account details.

Get Account Stats

Tool to retrieve usage statistics and performance metrics for the account.

Get Automation

Tool to retrieve details of a specific automation by ID.

Get Automation Activity

Tool to retrieve subscriber activity for a specific automation.

Get Campaign Languages

Tool to retrieve a list of all available campaign languages.

Get Campaigns

Tool to retrieve a list of all campaigns.

Get E-commerce Cart

Tool to fetch details of a specific cart by shop ID and cart ID.

Get E-commerce Cart Item

Tool to fetch details of a specific cart item by shop ID, cart ID, and item ID.

Get E-commerce Category

Tool to fetch details of a specific product category by shop and category ID.

Get E-commerce Customer

Tool to fetch details of a customer by shop and customer ID.

Get E-commerce Customers

Tool to list customers for a specific shop.

Get E-commerce Order

Tool to fetch details of a specific e-commerce order by shop ID and order ID.

Get E-commerce Product

Tool to fetch details of a specific e-commerce product by shop and product ID.

Get E-commerce Shop

Tool to fetch details of a specific e-commerce shop by ID.

Get E-commerce Shops

Tool to list all e-commerce shops connected to the account.

Get Fields

Tool to retrieve all custom fields defined in the account.

Get Group

Tool to retrieve details of a specific subscriber group by ID.

Get Groups

Tool to retrieve all subscriber groups.

Get Group Subscribers

Tool to list subscribers within a group by ID.

Get Import Status

Tool to retrieve the status and detailed report of a subscriber import operation by import ID.

Get Segment

Tool to retrieve a specific segment by ID.

Get Segments

Tool to retrieve all segments in the account.

Get Segment Subscribers

Tool to retrieve all subscribers belonging to a specific segment.

Get Subscriber

Tool to fetch a single subscriber by ID or email address.

Get Subscriber Activity

Tool to fetch the activity log for a specific subscriber.

Get Subscribers

Tool to retrieve all subscribers.

Get Subscribers Stats

Tool to get subscriber statistics for the account.

Get Webhook

Tool to retrieve details of a specific webhook by ID.

Get Webhooks

Tool to retrieve all configured webhooks.

Import E-commerce Categories

Tool to bulk import categories to an e-commerce shop.

Import E-commerce Orders

Tool to bulk import orders to an e-commerce shop.

Import E-commerce Products

Tool to bulk import products to an e-commerce shop.

Import Subscribers to Group

Tool to bulk import multiple subscribers to a specific group.

List Automations

Tool to retrieve all automations in your MailerLite account.

List E-commerce Cart Items

Tool to list all items in a specific cart for an e-commerce shop.

List E-commerce Carts

Tool to list all carts for a specific shop.

List E-commerce Categories

Tool to list all product categories for a shop.

List E-commerce Category Products

Tool to list all products in a specific e-commerce category.

List E-commerce Orders

Tool to list all orders for a specific e-commerce shop.

List E-commerce Products

Tool to list all products for a specific e-commerce shop.

List Forms

Tool to retrieve all forms of a specific type (popup, embedded, or promotion).

List Timezones

Tool to retrieve all available timezones supported by MailerLite.

Remove Product From Category

Tool to remove a product from a category in an e-commerce shop.

Remove Subscriber From Group

Tool to remove a subscriber from a group by ID.

Set Double Opt-In

Tool to enable or disable double opt-in for new subscribers.

Update E-commerce Cart

Tool to update an existing cart's checkout URL or total price.

Update E-commerce Cart Item

Tool to update a cart item's quantity or properties in an e-commerce cart.

Update E-commerce Category

Tool to update an existing product category in an e-commerce shop.

Update E-commerce Customer

Tool to update a customer's data for a shop by IDs.

Update E-commerce Order

Tool to update an existing order's status or total price in an e-commerce shop.

Update E-commerce Product

Tool to update an existing product in an e-commerce shop by IDs.

Update E-commerce Shop

Tool to update settings of a connected e-commerce shop by ID.

Update Field

Tool to update the title of an existing custom field.

Update Group

Tool to update a group's name by ID.

Update Segment

Tool to rename an existing segment by ID.

Update Subscriber

Tool to update an existing subscriber's information by ID.

Update Webhook

Tool to update an existing MailerLite webhook.

FRAMEWORKS

How to build Mailerlite MCP Agent with another framework

OpenAI Agents SDK

Use Mailerlite MCP with OpenAI Agents SDK

Claude Code

Use Mailerlite MCP with Claude Code

Claude Cowork

Use Mailerlite MCP with Claude Cowork

Codex

Use Mailerlite MCP with Codex

OpenClaw

Use Mailerlite MCP with OpenClaw

Hermes

Use Mailerlite MCP with Hermes

CLI

Use Mailerlite MCP with CLI

Google ADK

Use Mailerlite MCP with Google ADK

LangChain

Use Mailerlite MCP with LangChain

Vercel AI SDK

Use Mailerlite MCP with Vercel AI SDK

Mastra AI

Use Mailerlite MCP with Mastra AI

LlamaIndex

Use Mailerlite MCP with LlamaIndex

CrewAI

Use Mailerlite MCP with CrewAI

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FAQ

Frequently asked questions

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

Yes, you can. Claude Agent SDK 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 Mailerlite tools.

Yes, absolutely. You can configure which Mailerlite 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 Mailerlite data and credentials are handled as safely as possible.

Start with Mailerlite.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Mailerlite 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 Mailerlite MCP with Claude Agent SDK

Connect Mailerlite without auth hassles

Introduction

Also integrate Mailerlite with

TL;DR

What is Claude Agent SDK?

What is the Mailerlite 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 Claude/Anthropic and Composio

Install dependencies

Set up environment variables

Import dependencies

Create a Composio instance and Tool Router session

Configure Claude Agent with MCP

Create client and start chat loop

Run the application

Complete Code

Conclusion

Supported Tools

How to build Mailerlite MCP Agent with another framework

OpenAI Agents SDK

Claude Code

Claude Cowork

Codex

OpenClaw

Hermes

CLI

Google ADK

LangChain

Vercel AI SDK

Mastra AI

LlamaIndex

CrewAI

Explore Other Toolkits

Reddit

Facebook

Linkedin

Active campaign

Frequently asked questions

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

Can I use Tool Router MCP with Claude Agent SDK?+

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

How safe is my data with Composio Tool Router?+

Start with Mailerlite.It takes 30 seconds.

Teams ship real agents on Composio