How to integrate Square MCP with Mastra AI

This guide walks you through connecting Square to Mastra AI 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 Mastra AI 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

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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.

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Introduction

This guide will help you understand how to give your Mastra AI 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 SDK Claude Agent SDK Claude Code Claude Cowork Codex OpenClaw Hermes CLI Google ADK LangChain Vercel AI SDK LlamaIndex CrewAI

TL;DR

Here's what you'll learn:

Set up your environment so Mastra, OpenAI, and Composio work together
Create a Tool Router session in Composio that exposes Square tools
Connect Mastra's MCP client to the Composio generated MCP URL
Fetch Square tool definitions and attach them as a toolset
Build a Mastra agent that can reason, call tools, and return structured results
Run an interactive CLI where you can chat with your Square agent

What is Mastra AI?

Mastra AI is a TypeScript framework for building AI agents with tool support. It provides a clean API for creating agents that can use external services through MCP.

Key features include:

MCP Client: Built-in support for Model Context Protocol servers
Toolsets: Organize tools into logical groups
Step Callbacks: Monitor and debug agent execution
OpenAI Integration: Works with OpenAI models via @ai-sdk/openai

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:

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 step09 STEPS

Prerequisites

Before starting, make sure you have:

Node.js 18 or higher
A Composio account with an active API key
An OpenAI API key
Basic familiarity with TypeScript

Getting API Keys for OpenAI and Composio

OpenAI API Key

Go to the OpenAI dashboard and create an API key.
You need credits or a connected billing setup to use the models.
Store the key somewhere safe.

Composio API Key

Log in to the Composio dashboard.
Go to Settings and copy your API key.
This key lets your Mastra agent talk to Composio and reach Square through MCP.

Install dependencies

bash

npm install @composio/core @mastra/core @mastra/mcp @ai-sdk/openai dotenv

Install the required packages.

What's happening:

@composio/core is the Composio SDK for creating MCP sessions
@mastra/core provides the Agent class
@mastra/mcp is Mastra's MCP client
@ai-sdk/openai is the model wrapper for OpenAI
dotenv loads environment variables from .env

Set up environment variables

bash

COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_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
COMPOSIO_USER_ID tells Composio which user this session belongs to
OPENAI_API_KEY lets the Mastra agent call OpenAI models

Import libraries and validate environment

typescript

import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({
  apiKey: composioAPIKey as string,
});

What's happening:

dotenv/config auto loads your .env so process.env.* is available
openai gives you a Mastra compatible model wrapper
Agent is the Mastra agent that will call tools and produce answers
MCPClient connects Mastra to your Composio MCP server
Composio is used to create a Tool Router session

Create a Tool Router session for Square

typescript

async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["square"],
    },
  );

  const composioMCPUrl = session.mcp.url;
  console.log("Square MCP URL:", composioMCPUrl);

What's happening:

create spins up a short-lived MCP HTTP endpoint for this user
The toolkits array contains "square" for Square access
session.mcp.url is the MCP URL that Mastra's MCPClient will connect to

Configure Mastra MCP client and fetch tools

typescript

const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      nasdaq: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

console.log("Fetching MCP tools from Composio...");
const composioTools = await mcpClient.getTools();
console.log("Number of tools:", Object.keys(composioTools).length);

What's happening:

MCPClient takes an id for this client and a list of MCP servers
The headers property includes the x-api-key for authentication
getTools fetches the tool definitions exposed by the Square toolkit

Create the Mastra agent

typescript

const agent = new Agent({
    name: "square-mastra-agent",
    instructions: "You are an AI agent with Square tools via Composio.",
    model: "openai/gpt-5",
  });

What's happening:

Agent is the core Mastra agent
name is just an identifier for logging and debugging
instructions guide the agent to use tools instead of only answering in natural language
model uses openai("gpt-5") to configure the underlying LLM

Set up interactive chat interface

typescript

let messages: AiMessageType[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end.\n");

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  prompt: "> ",
});

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;
  }

  messages.push({
    id: crypto.randomUUID(),
    role: "user",
    content: trimmedInput,
  });

  console.log("\nAgent is thinking...\n");

  try {
    const response = await agent.generate(messages, {
      toolsets: {
        square: composioTools,
      },
      maxSteps: 8,
    });

    const { text } = response;

    if (text && text.trim().length > 0) {
      console.log(`Agent: ${text}\n`);
        messages.push({
          id: crypto.randomUUID(),
          role: "assistant",
          content: text,
        });
      }
    } catch (error) {
      console.error("\nError:", error);
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    console.log("\nSession ended.");
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(1);
});

What's happening:

messages keeps the full conversation history in Mastra's expected format
agent.generate runs the agent with conversation history and Square toolsets
maxSteps limits how many tool calls the agent can take in a single run
onStepFinish is a hook that prints intermediate steps for debugging

Complete Code

Here's the complete code to get you started with Square and Mastra AI:

typescript

import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({ apiKey: composioAPIKey as string });

async function main() {
  const session = await composio.create(composioUserID as string, {
    toolkits: ["square"],
  });

  const composioMCPUrl = session.mcp.url;

  const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      square: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "square-mastra-agent",
    instructions: "You are an AI agent with Square tools via Composio.",
    model: "openai/gpt-5",
  });

  let messages: AiMessageType[] = [];

  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: "> ",
  });

  rl.prompt();

  rl.on("line", async (input: string) => {
    const trimmed = input.trim();
    if (["exit", "quit"].includes(trimmed.toLowerCase())) {
      rl.close();
      return;
    }

    messages.push({ id: crypto.randomUUID(), role: "user", content: trimmed });

    const { text } = await agent.generate(messages, {
      toolsets: { square: composioTools },
      maxSteps: 8,
    });

    if (text) {
      console.log(`Agent: ${text}\n`);
      messages.push({ id: crypto.randomUUID(), role: "assistant", content: text });
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main();

Conclusion

You've built a Mastra AI agent that can interact with Square through Composio's Tool Router. You can extend this further by:

Adding other toolkits like Gmail, Slack, or GitHub
Building a web-based chat interface around this agent
Using multiple MCP endpoints to enable cross-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

Use Square MCP with OpenAI Agents SDK

Claude Agent SDK

Use Square MCP with Claude Agent SDK

Claude Code

Use Square MCP with Claude Code

Claude Cowork

Use Square MCP with Claude Cowork

Codex

Use Square MCP with Codex

OpenClaw

Use Square MCP with OpenClaw

Hermes

Use Square MCP with Hermes

CLI

Use Square MCP with CLI

Google ADK

Use Square MCP with Google ADK

LangChain

Use Square MCP with LangChain

Vercel AI SDK

Use Square MCP with Vercel AI SDK

LlamaIndex

Use Square MCP with LlamaIndex

CrewAI

Use Square MCP with CrewAI

MORE TOOLKITS

Explore Other Toolkits

Toolkit marketplace

Addresszen

Api Key

Addresszen is a real-time address autocomplete and verification service. It helps capture accurate, deliverable addresses with instant suggestions and validation.

Asin data api

Api Key

Asin data api gives you detailed, real-time product data from Amazon, including price, rank, and reviews. Perfect for e-commerce pros and data-driven marketers who need instant marketplace insights.

Baselinker

Api Key

BaseLinker is an all-in-one e-commerce management platform connecting stores, marketplaces, carriers, and more. It streamlines order processing, inventory control, and automates your sales operations.

Bestbuy

Api Key

Best Buy is a leading retailer offering APIs for product, store, and recommendation data. Instantly access up-to-date retail insights for smarter shopping and decision-making.

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. Mastra AI 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.

Start with Square.It takes 30 seconds.

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

Start building

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 Square MCP with Mastra AI

Connect Square without auth hassles

Introduction

Also integrate Square with

TL;DR

What is Mastra AI?

What is the Square 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 libraries and validate environment

Create a Tool Router session for Square

Configure Mastra MCP client and fetch tools

Create the Mastra agent

Set up interactive chat interface

Complete Code

Conclusion

Supported Tools

How to build Square MCP Agent with another framework

OpenAI Agents SDK

Claude Agent SDK

Claude Code

Claude Cowork

Codex

OpenClaw

Hermes

CLI

Google ADK

LangChain

Vercel AI SDK

LlamaIndex

CrewAI

Explore Other Toolkits

Addresszen

Asin data api

Baselinker

Bestbuy

Frequently asked questions

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

Can I use Tool Router MCP with Mastra AI?+

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

How safe is my data with Composio Tool Router?+

Start with Square.It takes 30 seconds.

Teams ship real agents on Composio