How to integrate Postalytics MCP with LangChain

This guide walks you through connecting Postalytics to LangChain using the Composio tool router. By the end, you'll have a working Postalytics agent that can create a new direct mail campaign, sync contacts from hubspot to postalytics, track delivery status for recent campaigns through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Postalytics account through Composio's Postalytics MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Postalytics is cloud-based direct mail automation software for marketing teams. It streamlines campaign creation, tracking, and CRM integration with digital-like automation.

24 Tools

Introduction

This guide walks you through connecting Postalytics to LangChain using the Composio tool router. By the end, you'll have a working Postalytics agent that can create a new direct mail campaign, sync contacts from hubspot to postalytics, track delivery status for recent campaigns through natural language commands.

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

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

Also integrate Postalytics 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 Postalytics project to Composio
  • Create a Tool Router MCP session for Postalytics
  • Initialize an MCP client and retrieve Postalytics tools
  • Build a LangChain agent that can interact with Postalytics
  • 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 Postalytics MCP server, and what's possible with it?

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

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

Configure the agent with the MCP URL

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

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

Add Account

Tool to create a new sub-account in the Postalytics system.

Add Contact

Tool to add a contact to a specified contact list with their information.

Create New Campaign

Tool to create a new direct mail campaign in Postalytics.

Create Suppression List

Tool to create a new suppression list that can be used in campaigns to suppress contacts from being sent mail.

Create Suppression List Contact

Tool to create a new suppression contact on a specified suppression list.

Create Template

Tool to create a new template with full HTML for postcard or letter.

Create Webhook

Tool to create a new webhook to receive campaign event notifications from Postalytics.

Delete Account

Tool to delete a Postalytics account and all associated campaigns, templates, and lists.

Delete Campaign

Tool to delete a campaign from the system.

Delete Suppression List

Tool to delete a specified suppression list.

Delete Suppression List Contact

Tool to delete a specific contact from a suppression list.

Get All Contact Lists

Tool to retrieve all contact lists for an account.

Get All Contacts on a List

Tool to retrieve all contacts from a specified contact list with pagination support.

Get All Drip Campaigns

Tool to retrieve all triggered drip campaign names and endpoint IDs in the account.

Get All Flows

Tool to retrieve all flows for the requester's account.

Get All Webhooks

Tool to retrieve all webhooks configured for the authenticated account.

Get Integrations

Tool to retrieve all Connect integrations configured for the authenticated user's account.

Get My Account

Tool to retrieve basic account information for the authenticated user.

Get Suppression List

Tool to get the details of a suppression list based on the id supplied.

Get Suppression List Contact

Tool to retrieve a specific contact from a suppression list.

Get Suppression List Contacts

Tool to get all contacts on a specified suppression list.

Get Suppression Lists

Tool to retrieve all suppression lists for the authenticated user.

Update Account

Tool to update an existing account in the Postalytics system.

Update Suppression List Contact

Tool to update a suppression contact on the specified suppression list.

FRAMEWORKS

How to build Postalytics MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Postalytics MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Postalytics MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Postalytics MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Postalytics MCP with Claude Cowork

Codex logo

Codex

Use Postalytics MCP with Codex

OpenClaw logo

OpenClaw

Use Postalytics MCP with OpenClaw

Hermes logo

Hermes

Use Postalytics MCP with Hermes

CLI logo

CLI

Use Postalytics MCP with CLI

Google ADK logo

Google ADK

Use Postalytics MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Postalytics MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Postalytics MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Postalytics MCP with LlamaIndex

CrewAI logo

CrewAI

Use Postalytics MCP with CrewAI

FAQ

Frequently asked questions

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

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

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