How to integrate Constant Contact MCP with LangChain

This guide walks you through connecting Constant Contact to LangChain using the Composio tool router. By the end, you'll have a working Constant Contact agent that can create newsletter draft for new subscribers, list contacts added this week, segment inactive constant contact subscribers through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Constant Contact account through Composio's Constant Contact MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Constant Contact is an email marketing and automation platform for small businesses. It helps teams build campaigns, manage contacts, and grow customer relationships.

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Introduction

This guide walks you through connecting Constant Contact to LangChain using the Composio tool router. By the end, you'll have a working Constant Contact agent that can create newsletter draft for new subscribers, list contacts added this week, segment inactive constant contact subscribers through natural language commands.

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

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

Also integrate Constant Contact with

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TL;DR

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

The Constant Contact MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Constant Contact account. It provides structured and secure access so your agent can perform Constant Contact 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 Constant Contact 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 Constant Contact 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: ['constant_contact']
    }
);

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

Configure the agent with the MCP URL

const client = new MultiServerMCPClient({
    "constant_contact-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 Constant Contact MCP server via HTTP
  • The client is configured with a name and the URL from our Tool Router session
  • getTools() retrieves all available Constant Contact 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 Constant Contact 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 Constant Contact 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: ['constant_contact']
        }
    );

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

Add Account Email Address

Add a new email address to a Constant Contact account.

Add Contact Taggings

Add Tags to Contacts.

Add list memberships

Add Contacts to Lists creates an activity to add contacts to one or more contact lists.

Copy Event

POST (copy) an existing event in Constant Contact.

Count Contact Consents

GET contact consent counts for a Constant Contact account.

Create Contact

Create a new contact in Constant Contact.

Create contact from sign-up form

Create or Update a Contact via sign-up form.

Create Contact List

Create a new contact list in Constant Contact.

Create contact tag

POST (Create) a Tag.

Create Custom Field

Create a new custom field for contacts in Constant Contact.

Create Email Campaign

Create a new email campaign in Constant Contact.

Create Event

Create a new event with default settings in Constant Contact.

Create Resend to Non-openers

Create a resend to non-openers campaign activity for an email campaign.

Create Social Post

Create a new social media post campaign.

Delete contact

DELETE a specific contact from your Constant Contact account.

Delete Contact List

Permanently deletes a contact list from Constant Contact by its ID.

Create contact delete activity

Delete multiple contacts in bulk by submitting a contact_delete activity.

Delete contact tag

Delete a specific contact tag from your Constant Contact account.

Delete contact tags

Delete one or more tags from contacts in Constant Contact.

Delete custom field

DELETE a specific contact custom field from your Constant Contact account.

Delete custom fields

Delete one or more custom fields from a Constant Contact account.

Delete Email Campaign

DELETE an Email Campaign from your Constant Contact account.

Delete contact list activity

Delete one or more contact lists from your Constant Contact account by submitting a list delete activity.

Delete Segment

Permanently deletes a segment from Constant Contact by its ID.

Export Contacts

Create a bulk activity that exports contacts to a CSV file.

Get account physical address

GET the Physical Address for the Account.

Get account summary

GET a summary of account details for a Constant Contact account.

Get activity status

GET the status of a specific bulk activity.

Get contact

GET a contact by their unique ID.

Get contact activity summary report

GET contact tracking activity summary for a specific contact.

Get Contact List

GET details for a specific contact list by its ID.

Get Contact Open and Click Rates Report

GET average open and click rates for a contact.

Get Contacts Export File

Retrieve the exported contacts file from a completed export contacts activity.

Get Contact SMS Engagement History

GET SMS Engagement History for a Contact.

Get contact tag details

GET Tag Details - Retrieves detailed information about a specific contact tag.

Get custom field

GET a custom field by its unique ID.

Get email campaign details

GET details for a single email campaign using its campaign ID.

Get Email Campaign Activity

GET details for a specific email campaign activity by its ID.

Get email campaign activity preview

GET the HTML Preview of an Email Campaign Activity.

Get Email Campaign Activity Schedule

GET an email campaign activity schedule.

Get email campaign activity send history

GET the send history of an email campaign activity.

Get email campaign ID cross-references

GET a collection of V2 and V3 API Email Campaign ID cross-references.

Get Email Campaign Statistics Report

GET statistics for one or more email campaigns.

Get Event

GET details for a single event by its unique ID.

Get list ID cross-references

GET a collection of V2 and V3 API List IDs cross-references.

Get Partner Webhook Subscription

GET details for a specific Partner Webhook Topic Subscription by its ID.

Get resend to non-openers

GET Details for a Resend to Non-openers Campaign Activity.

Get Segment

GET details for a specific segment by its unique ID.

Import contacts from CSV file

Import contacts into Constant Contact from a CSV file.

Import contacts from JSON

Bulk import contacts into Constant Contact using JSON format.

List account email addresses

GET a Collection of Account Email Addresses.

List account user privileges

Get the user privileges associated with your access token.

List activity statuses

GET a collection of bulk activities.

List Contact Lists

GET all contact lists for the Constant Contact account.

List contacts

GET Contacts Collection to retrieve a list of contacts from Constant Contact.

List contact tags

GET Details for All Tags - Retrieves all contact tags for the account.

List contact custom fields

GET custom_fields Collection to retrieve all contact custom field definitions.

List Email Campaigns

GET a collection of email campaigns from Constant Contact.

List Email Campaign Summaries Report

GET an Email Campaigns Summary Report from Constant Contact.

List Email Did Not Opens Report

GET an Email Did Not Opens Report to retrieve a list of contacts who did not open a specific email campaign.

List email forwards report

GET an Email Forwards Report for a specific email campaign activity.

List email opt-outs report

GET an Email Opt-outs Report for a specific email campaign activity.

List Email Unique Opens Report

GET an email unique opens report for a campaign activity.

List Events

GET a collection of events from Constant Contact.

List event track registrations

GET registrations for an event track to retrieve a list of registrations.

List Landing Page Contact Opens Report

GET a Contacts Opens Landing Page Report.

List Landing Page Unique Contact Adds Report

GET a Unique Contacts Adds Landing Page Report for a specific landing page campaign activity.

List Landing Page Unique Contact Clicks Report

GET unique contact clicks data for a landing page campaign.

List Landing Page Unique Contact Opens Report

GET a Unique Contacts Opens Landing Page Report to retrieve a list of contacts who uniquely opened a specific landing page campaign.

List landing page unique contact updates report

GET a Unique Contacts Updates Landing Page Report for a specific landing page campaign activity.

List Segments

GET all segments for the Constant Contact account.

List SMS Campaign Summaries Report

GET an SMS Campaigns Summary Report.

List Social Connections

GET social network connections for a Constant Contact account.

List Social Hashtag Groups

GET hashtag groups - Retrieves a paginated list of social hashtag groups.

List Social Profiles

GET social media profiles from Constant Contact.

Remove Contact Tagging

Remove tagging from contacts in Constant Contact.

Remove Tags from Contacts

Remove tags from contacts in Constant Contact.

Remove contacts from lists

Create a Remove Contacts from Lists activity to remove contacts from one or more lists.

Rename Email Campaign

PATCH (Update) the name of an existing email campaign in Constant Contact.

Rename Segment

PATCH (rename) an existing segment in Constant Contact.

Resubscribe Contact

Resubscribe an unsubscribed contact to one or more contact lists.

Undo Event Ticket Check-In

Undo check-in for event tickets.

Update Account Details

PUT (update) Account Details for the authenticated user.

Update Account Physical Address

PUT (update) the Physical Address for an Account.

Update Contact

PUT (update) an existing contact in Constant Contact.

Update Contact List

PUT (update) an existing contact list in Constant Contact.

Update Contact Tag

PUT (Update) a Tag.

Update Custom Field

Update an existing contact custom field in Constant Contact.

Update Email Campaign Activity

PUT (Update) an Email Campaign Activity in Constant Contact.

Update Event

PATCH (update) an existing event in Constant Contact.

Update Event Track Registration Payment Status

Update the payment status for event track registrations in Constant Contact.

Update Event Track Registrations

PUT (update) registration status for event track registrations.

Update Segment

PUT (update) an existing segment in Constant Contact.

FRAMEWORKS

How to build Constant Contact MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Constant Contact MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Constant Contact MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Constant Contact MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Constant Contact MCP with Claude Cowork

Codex logo

Codex

Use Constant Contact MCP with Codex

OpenClaw logo

OpenClaw

Use Constant Contact MCP with OpenClaw

Hermes logo

Hermes

Use Constant Contact MCP with Hermes

CLI logo

CLI

Use Constant Contact MCP with CLI

Google ADK logo

Google ADK

Use Constant Contact MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Constant Contact MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Constant Contact MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Constant Contact MCP with LlamaIndex

CrewAI logo

CrewAI

Use Constant Contact MCP with CrewAI

FAQ

Frequently asked questions

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

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

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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.

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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.

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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.

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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.

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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.

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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.

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