How to integrate Square MCP with LangChain

This guide walks you through connecting Square to LangChain using the Composio tool router. By the end, you'll have a working Square agent that can create and send an invoice to a customer, list all recent payments from last week, update item prices in your product catalog through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Square account through Composio's Square MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Square is a platform for payment processing, POS, invoicing, and e-commerce. It empowers businesses to accept payments, manage sales, and streamline operations from one place.

96 Tools

Introduction

This guide walks you through connecting Square to LangChain using the Composio tool router. By the end, you'll have a working Square agent that can create and send an invoice to a customer, list all recent payments from last week, update item prices in your product catalog through natural language commands.

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

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

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

The Square MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Square account. It provides structured and secure access to your Square business tools, so your agent can perform actions like processing payments, managing invoices, tracking orders, handling customers, and managing inventory on your behalf.

  • Seamless payment processing: Let your agent accept card payments, issue refunds, and manage transactions across your business locations.
  • Automated invoice creation and management: Ask your agent to generate, send, and monitor invoices for your customers, streamlining your billing process.
  • Order and fulfillment tracking: Enable your agent to view, update, and manage orders, helping you keep tabs on fulfillment and delivery status with ease.
  • Customer profile management: Have your agent create, update, or search customer profiles, making it easier to personalize service and maintain up-to-date records.
  • Inventory and item catalog control: Allow your agent to track stock levels, update item details, and organize your catalog for smooth retail operations.

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 Square 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 Square 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: ['square']
    }
);

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

Configure the agent with the MCP URL

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

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

Accept Dispute

Accept a dispute and acknowledge liability, returning funds to the cardholder.

Add Group to Customer

Tool to add a customer to a customer group.

Calculate Order

Tool to preview order pricing without creating an order.

Cancel Invoice

Cancels a Square invoice, preventing further payments from being collected.

Cancel Payment

Cancels (voids) a payment that is in APPROVED status.

Create Bulk Customers

Tool to create multiple customer profiles in a single request.

Create Card

Tool to create a card on file.

Create Customer

Tool to create a new customer profile in Square.

Create Customer Custom Attribute Definition

Tool to create a customer-related custom attribute definition.

Create Customer Group

Tool to create a new customer group for a business.

Create Dispute Evidence File

Tool to upload a file as dispute evidence.

Create Dispute Evidence Text

Upload text evidence for a dispute challenge.

Create Invoice Attachment

Upload and attach a file to a Square invoice.

Create Location

Tool to create a new business location in a Square account.

Create Location Custom Attribute Definition

Tool to create a location-related custom attribute definition.

Delete Customer

Tool to delete a Square customer profile.

Delete Customer Custom Attribute

Tool to delete a custom attribute from a customer profile.

Delete Customer Custom Attribute Definition

Tool to delete a customer-related custom attribute definition.

Delete Customer Group

Tool to delete a customer group by its ID.

Bulk Delete Customers

Tool to bulk delete customer profiles from Square.

Delete Dispute Evidence

Removes a specific piece of evidence from a dispute.

Delete Invoice

Tool to delete a Square invoice (only DRAFT invoices can be deleted).

Delete Invoice Attachment

Tool to delete an attachment from a Square invoice.

Delete Location Custom Attribute

Tool to delete a custom attribute from a location.

Delete Location Custom Attribute Definition

Tool to delete a location-related custom attribute definition.

Delete Locations Custom Attributes (Batch)

Tool to delete custom attributes from multiple locations in a single batch request.

Delete Merchant Custom Attribute

Tool to delete a custom attribute from a merchant profile.

Delete Merchant Custom Attribute Definition

Tool to delete a merchant-related custom attribute definition.

Delete Merchants Custom Attributes (Batch)

Tool to delete custom attributes from multiple merchants in a single batch request.

Delete Webhook Subscription

Permanently deletes a webhook subscription by its ID.

Get Business Booking Profile

Tool to retrieve the business booking profile for a Square merchant via GraphQL.

Get Current Merchant

Tool to retrieve merchant information associated with the access token using Square's GraphQL API.

Get Customer Custom Attribute

Retrieves a custom attribute from a customer profile in Square.

Get Customer Custom Attribute Definition

Tool to retrieve a customer-related custom attribute definition from Square.

Get Customers via GraphQL

Tool to retrieve customer profiles from Square Customer Directory using GraphQL API.

Get Dispute Evidence

Retrieves detailed information about a specific piece of evidence that was uploaded for a dispute.

Get Invoice

Retrieves detailed information about a specific Square invoice by its ID.

Get Merchant

Tool to retrieve detailed information about a specific Square merchant by ID.

Get Online Checkout Location Settings

Tool to retrieve location-level settings for Square online checkout.

List Channels

Tool to list requested channels from Square.

List Customer Custom Attribute Definitions

Tool to list customer-related custom attribute definitions from Square.

List Customer Custom Attribute Definitions (GraphQL)

Tool to retrieve customer custom attribute definitions via Square's GraphQL API.

List Customer Custom Attributes

Tool to list custom attributes for a customer profile.

List Customer Groups

Tool to retrieve the list of customer groups of a business.

List Customers

Tool to retrieve customer profiles associated with a Square account.

List Customer Segments

Tool to retrieve the list of customer segments of a business.

List Dispute Evidence

Tool to list evidence items associated with a given dispute.

List Invoices

Tool to list invoices for a Square location.

List Location Custom Attribute Definitions

Tool to list location-related custom attribute definitions from Square.

List Locations

Tool to retrieve all business locations from a Square account.

List Locations Custom Attributes

Tool to list custom attributes for a specific location in Square.

List Merchant Custom Attribute Definitions

Tool to list merchant-related custom attribute definitions from Square.

List Merchants

Tool to retrieve merchant account information associated with the access token.

List Merchants Custom Attributes

Tool to list custom attributes for a specific merchant in Square.

List Payments

Tool to list payments by location and time range to enable reconciliation and net sales reporting from Square POS.

List Webhook Event Types

Tool to list available webhook event types.

List Webhook Subscriptions

List all webhook subscriptions owned by your application.

Remove Group From Customer

Removes a customer from a customer group.

Retrieve Bulk Customers

Tool to retrieve multiple customer profiles in a single request.

Retrieve Channel

Retrieve a Square channel by its ID.

Bulk Retrieve Channels

Tool to bulk retrieve multiple Square channels by their IDs in a single request.

Retrieve Customer

Tool to retrieve detailed information about a specific Square customer by ID.

Retrieve Customer Group

Tool to retrieve a specific Square customer group by ID.

Retrieve Customer Segment

Tool to retrieve a specific customer segment by its ID.

Retrieve Dispute

Tool to retrieve a Square dispute by ID.

Retrieve Location

Tool to retrieve detailed information about a specific Square location by ID.

Retrieve Location Custom Attribute

Retrieves a custom attribute associated with a location in Square.

Retrieve Location Custom Attribute Definition

Tool to retrieve a location-related custom attribute definition.

Retrieve Merchant Custom Attribute

Retrieves a custom attribute associated with a merchant in Square.

Retrieve Merchant Custom Attribute Definition

Tool to retrieve a merchant-related custom attribute definition from Square.

Retrieve Merchants

Tool to retrieve merchant information including status, main location details, and capabilities using Square's GraphQL API.

Retrieve Order

Retrieves detailed information about a specific Square order by its ID.

Retrieve Payment Link

Retrieves a Square-hosted payment link by ID.

Retrieve Token Status

Tool to retrieve information about an OAuth access token or personal access token.

Retrieve Webhook Subscription

Retrieve a Square webhook subscription by its ID.

Search Customers

Tool to search customer profiles in Square Customer Directory.

Search Orders

Tool to search orders across one or more Square locations with filters.

Submit Dispute Evidence

Submits evidence for a dispute to the cardholder's bank.

Test Webhook Subscription

Tests a webhook subscription by sending a test event to the configured notification URL.

Update Customer

Tool to update an existing Square customer profile.

Update Customer Custom Attribute Definition

Tool to update a customer-related custom attribute definition in Square.

Update Customer Group

Tool to update a customer group's information by its ID.

Bulk Update Customers

Tool to update multiple customer profiles in a single batch operation.

Update Location

Tool to update an existing business location in a Square account.

Update Location Custom Attribute Definition

Tool to update a location-related custom attribute definition in Square.

Update Merchant Custom Attribute Definition

Tool to update a merchant-related custom attribute definition in Square.

Update Online Checkout Location Settings

Tool to update location-level settings for Square online checkout.

Update Order

Updates an existing Square order by adding, modifying, or removing fields.

Update Webhook Subscription

Tool to update a Square webhook subscription.

Update Webhook Subscription Signature Key

Tool to rotate the signature key for a webhook subscription.

Upsert Customer Custom Attribute

Tool to create or update a custom attribute for a customer profile.

Batch Upsert Customer Custom Attributes

Tool to create or update custom attributes for multiple customers in a single batch request.

Upsert Location Custom Attribute

Tool to create or update a custom attribute for a location.

Batch Upsert Locations Custom Attributes

Tool to create or update custom attributes for multiple locations in a single batch request.

Upsert Merchant Custom Attribute

Tool to create or update a custom attribute for a merchant profile.

Batch Upsert Merchants Custom Attributes

Tool to create or update custom attributes for multiple merchants in a single batch request.

FRAMEWORKS

How to build Square MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Square MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Square MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Square MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Square MCP with Claude Cowork

Codex logo

Codex

Use Square MCP with Codex

OpenClaw logo

OpenClaw

Use Square MCP with OpenClaw

Hermes logo

Hermes

Use Square MCP with Hermes

CLI logo

CLI

Use Square MCP with CLI

Google ADK logo

Google ADK

Use Square MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Square MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Square MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Square MCP with LlamaIndex

CrewAI logo

CrewAI

Use Square MCP with CrewAI

FAQ

Frequently asked questions

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

Yes, absolutely. You can configure which Square 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 Square 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.

Harsha Gaddipati
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
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
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
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
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
Jerome Leclanche
Co-Founder, Ingram Technologies