How to integrate Laposta MCP with LangChain

This guide walks you through connecting Laposta to LangChain using the Composio tool router. By the end, you'll have a working Laposta agent that can add subscriber to laposta list by email, send campaign to "monthly updates" group, get open rates for last laposta campaign through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Laposta account through Composio's Laposta MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Laposta is a Dutch newsletter platform for creating and sending professional newsletters. It makes email marketing simple and efficient for teams and businesses.

24 Tools

Introduction

This guide walks you through connecting Laposta to LangChain using the Composio tool router. By the end, you'll have a working Laposta agent that can add subscriber to laposta list by email, send campaign to "monthly updates" group, get open rates for last laposta campaign through natural language commands.

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

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

Also integrate Laposta with

OpenAI Agents SDKClaude Agent SDKClaude CodeClaude CoworkCodexOpenClawHermesCLIGoogle ADKVercel AI SDKMastra AILlamaIndexCrewAI

TL;DR

Here's what you'll learn:
  • Get and set up your OpenAI and Composio API keys
  • Connect your Laposta project to Composio
  • Create a Tool Router MCP session for Laposta
  • Initialize an MCP client and retrieve Laposta tools
  • Build a LangChain agent that can interact with Laposta
  • 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 Laposta MCP server, and what's possible with it?

The Laposta MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Laposta account. It provides structured and secure access so your agent can perform Laposta operations on your behalf.

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 step10 STEPS
1

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
2

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.
3

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
4

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
5

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 Laposta functionality through MCP
6

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 Laposta tools
  • Validating that COMPOSIO_USER_ID is also set before proceeding
7

Create a Tool Router session

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

const url = session.mcp.url;
What's happening:
  • We're creating a Tool Router session that gives your agent access to Laposta 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 Laposta tools as needed
8

Configure the agent with the MCP URL

const client = new MultiServerMCPClient({
    "laposta-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 Laposta MCP server via HTTP
  • The client is configured with a name and the URL from our Tool Router session
  • getTools() retrieves all available Laposta tools that the agent can use
  • We're creating a LangChain agent using the GPT-5 model
9

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 Laposta 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
10

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 Laposta 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: ['laposta']
        }
    );

    const url = session.mcp.url;
    
    const client = new MultiServerMCPClient({
        "laposta-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 Laposta 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 Laposta 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 Laposta action and event your agent gets out of the box.

Get All Campaigns

Tool to retrieve all campaigns from Laposta account.

Create Custom Field

Tool to create a custom field for a mailing list to define subscriber attributes.

Delete Field

Tool to permanently remove a custom field from a mailing list.

Get Field Details

Tool to retrieve specific field details by field_id.

Get All Fields

Tool to retrieve all fields for a specific list in Laposta.

Update Field

Tool to modify field configuration in a Laposta list.

Clear All Members From List

Tool to clear all active members from a list.

Create Mailing List

Tool to create a new mailing list in Laposta to manage email subscribers.

Delete List

Tool to permanently remove a mailing list from Laposta.

Get List Details

Tool to retrieve specific list details by list_id.

Get All Lists

Tool to retrieve all mailing lists from your Laposta account.

Update Mailing List

Tool to modify list properties such as name, remarks, or notification emails.

Create Member

Tool to add a new subscriber relationship to a list with custom fields and tracking info.

Delete Member

Tool to permanently remove a member from a list.

Get Member

Tool to retrieve specific member details by member_id or email.

Get All Members

Tool to retrieve all members from a specified Laposta mailing list.

Update Member

Tool to modify member data, status, or custom fields in a Laposta list.

Get All Campaign Reports

Tool to retrieve performance metrics for all campaigns.

Get All Segments

Tool to retrieve all segments from a mailing list.

Create Webhook

Tool to register a new webhook for list events in Laposta.

Delete Webhook

Tool to permanently remove a webhook.

Get Webhook Details

Tool to retrieve specific webhook details by webhook_id.

Get All Webhooks

Tool to retrieve all webhooks for a specific list.

Update Webhook

Tool to modify webhook configuration including URL, event type, or blocked status.

FRAMEWORKS

How to build Laposta MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Laposta MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Laposta MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Laposta MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Laposta MCP with Claude Cowork

Codex logo

Codex

Use Laposta MCP with Codex

OpenClaw logo

OpenClaw

Use Laposta MCP with OpenClaw

Hermes logo

Hermes

Use Laposta MCP with Hermes

CLI logo

CLI

Use Laposta MCP with CLI

Google ADK logo

Google ADK

Use Laposta MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Laposta MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Laposta MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Laposta MCP with LlamaIndex

CrewAI logo

CrewAI

Use Laposta MCP with CrewAI

FAQ

Frequently asked questions

With a standalone Laposta MCP server, the agents and LLMs can only access a fixed set of Laposta tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Laposta 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 Laposta tools.

Yes, absolutely. You can configure which Laposta 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 Laposta 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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