How to integrate Handwrytten MCP with LangChain

This guide walks you through connecting Handwrytten to LangChain using the Composio tool router. By the end, you'll have a working Handwrytten agent that can send a thank you card to john doe, schedule a handwritten birthday note delivery, list all pending handwrytten orders through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Handwrytten account through Composio's Handwrytten MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Introduction

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

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

Also integrate Handwrytten with

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

TL;DR

Here's what you'll learn:

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

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

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 step10 STEPS

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

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.

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

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

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 Handwrytten functionality through MCP

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 Handwrytten tools
Validating that COMPOSIO_USER_ID is also set before proceeding

Create a Tool Router session

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

const url = session.mcp.url;

What's happening:

We're creating a Tool Router session that gives your agent access to Handwrytten 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 Handwrytten tools as needed

Configure the agent with the MCP URL

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

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 Handwrytten 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

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 Handwrytten 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: ['handwrytten']
        }
    );

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

Add Recipient

Tool to add a recipient address to the user's addressbook in Handwrytten.

Calculate Order Taxes

Tool to calculate taxes for Handwrytten basket orders.

Check Authentication

Tool to verify API key authentication validity for Handwrytten.

Clear Basket

Tool to clear all items from the shopping basket.

Create Template

Tool to create a new template for the current user.

Create User Address

Tool to create a new user address in Handwrytten.

Delete Custom Image

Tool to delete a custom image/logo from Handwrytten.

Delete Recipient Address

Tool to delete one or more recipient addresses from user's profile.

Delete Template

Tool to delete a user's template by its ID.

Get Basket (New Method)

Tool to retrieve the user's basket using the new method.

Get Basket Count

Tool to retrieve the count of items currently in the basket.

Get Basket Item

Tool to retrieve a basket item by its ID from Handwrytten.

Get Card Details

Tool to get detailed information about a specific card in the Handwrytten catalog.

Get List of Addresses

Tool to retrieve a list of all addresses associated with the user's account.

Get Random Cards

Tool to retrieve random cards from Handwrytten.

Get Template Details

Tool to get detailed information about a card text template in the Handwrytten catalog.

Get Current User Info

Tool to retrieve information about the currently authenticated user.

Get User Address

Tool to retrieve the authenticated user's address and billing information.

List Basket Orders Grouped

Tool to list all basket orders grouped by basket.

List Past Baskets

Tool to retrieve a list of user's past baskets.

List Cards

Tool to retrieve a list of available Handwrytten cards with optional filtering and pagination.

List Categories

Tool to retrieve the list of available card categories from Handwrytten.

List Countries

Tool to retrieve the list of countries available in Handwrytten.

List Credit Cards

Tool to list all credit cards associated with the Handwrytten account.

List Fonts

Tool to retrieve the list of available handwriting fonts.

List Fonts for Customizer

Tool to list fonts available for use with the card customizer.

List Gift Cards

Tool to retrieve the list of available gift cards with their denominations and pricing.

List Custom User Images

Tool to retrieve a list of custom user images uploaded to Handwrytten.

List Inserts

Tool to retrieve a list of available inserts from Handwrytten.

List Orders

Tool to retrieve a list of user's past orders from Handwrytten.

List Orders Grouped

Tool to retrieve the user's order history grouped by basket.

List Past Orders

Tool to retrieve a list of user's past orders from Handwrytten API.

List Recipients

Tool to retrieve a list of recipient addresses that the user has previously saved.

List Signatures

Tool to retrieve the list of available signatures for use in card orders.

List States

Tool to retrieve the list of states/provinces available in Handwrytten.

List Template Categories

Tool to retrieve the list of available template categories from Handwrytten.

List Templates

Tool to retrieve a list of card text templates from Handwrytten.

Logout User

Tool to logout user from Handwrytten application.

Place Order in Basket

Tool to add an order to the basket in Handwrytten.

Tool to register a new Handwrytten user account.

Request Password Reset

Tool to request a password reset email for a Handwrytten account.

Set Default Address

Tool to set a default return address for the user in Handwrytten.

Set Test Mode

Tool to set test mode for the current Handwrytten user.

Update Basket Item

Tool to update an existing basket item in Handwrytten.

Update Billing Information

Tool to update user billing information (country, zip, address) for tax calculations in Handwrytten.

Update Recipient

Tool to update a recipient address in the user's addressbook in Handwrytten.

Update Template

Tool to update an existing user template in Handwrytten.

Upload Custom Logo

Tool to upload a custom image (logo or cover) to Handwrytten for use with custom cards.

FRAMEWORKS

How to build Handwrytten MCP Agent with another framework

OpenAI Agents SDK

Use Handwrytten MCP with OpenAI Agents SDK

Claude Agent SDK

Use Handwrytten MCP with Claude Agent SDK

Claude Code

Use Handwrytten MCP with Claude Code

Claude Cowork

Use Handwrytten MCP with Claude Cowork

Codex

Use Handwrytten MCP with Codex

OpenClaw

Use Handwrytten MCP with OpenClaw

Hermes

Use Handwrytten MCP with Hermes

CLI

Use Handwrytten MCP with CLI

Google ADK

Use Handwrytten MCP with Google ADK

Vercel AI SDK

Use Handwrytten MCP with Vercel AI SDK

Mastra AI

Use Handwrytten MCP with Mastra AI

LlamaIndex

Use Handwrytten MCP with LlamaIndex

CrewAI

Use Handwrytten MCP with CrewAI

MORE TOOLKITS

Explore Other Toolkits

Toolkit marketplace

Google Sheets

Oauth2

Google Sheets is a cloud-based spreadsheet tool for real-time collaboration and data analysis. It lets teams work together from anywhere, updating information instantly.

Notion

Oauth2Api Key

Notion is a collaborative workspace for notes, docs, wikis, and tasks. It streamlines team knowledge, project tracking, and workflow customization in one place.

Airtable

Oauth2Api Key

Airtable combines the flexibility of spreadsheets with the power of a database for easy project and data management. Teams use Airtable to organize, track, and collaborate with custom views and automations.

Asana

Oauth2

Asana is a collaborative work management platform for teams to organize and track projects. It streamlines teamwork, boosts productivity, and keeps everyone aligned on goals.

FAQ

Frequently asked questions

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

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

Start with Handwrytten.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Handwrytten tool your agent needs.Free to start.

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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 Handwrytten MCP with LangChain

Connect Handwrytten without auth hassles

Introduction

Also integrate Handwrytten with

TL;DR

What is LangChain?

What is the Handwrytten 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 OpenAI and Composio

Install dependencies

Set up environment variables

Import dependencies

Initialize Composio client

Create a Tool Router session

Configure the agent with the MCP URL

Set up interactive chat interface

Run the application

Complete Code

Conclusion

Supported Tools

How to build Handwrytten MCP Agent with another framework

OpenAI Agents SDK

Claude Agent SDK

Claude Code

Claude Cowork

Codex

OpenClaw

Hermes

CLI

Google ADK

Vercel AI SDK

Mastra AI

LlamaIndex

CrewAI

Explore Other Toolkits

Google Sheets

Notion

Airtable

Asana

Frequently asked questions

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

Can I use Tool Router MCP with LangChain?+

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

How safe is my data with Composio Tool Router?+

Start with Handwrytten.It takes 30 seconds.

Teams ship real agents on Composio