# How to integrate Brex MCP with Mastra AI

```json
{
  "title": "How to integrate Brex MCP with Mastra AI",
  "toolkit": "Brex",
  "toolkit_slug": "brex",
  "framework": "Mastra AI",
  "framework_slug": "mastra-ai",
  "url": "https://composio.dev/toolkits/brex/framework/mastra-ai",
  "markdown_url": "https://composio.dev/toolkits/brex/framework/mastra-ai.md",
  "updated_at": "2026-05-06T08:03:57.847Z"
}
```

## Introduction

This guide walks you through connecting Brex to Mastra AI using the Composio tool router. By the end, you'll have a working Brex agent that can create a new card for our intern, get the latest account statement pdf, add an expense for last week's conference through natural language commands.
This guide will help you understand how to give your Mastra AI agent real control over a Brex account through Composio's Brex MCP server.
Before we dive in, let's take a quick look at the key ideas and tools involved.

## Also integrate Brex with

- [OpenAI Agents SDK](https://composio.dev/toolkits/brex/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/brex/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/brex/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/brex/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/brex/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/brex/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/brex/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/brex/framework/cli)
- [Google ADK](https://composio.dev/toolkits/brex/framework/google-adk)
- [LangChain](https://composio.dev/toolkits/brex/framework/langchain)
- [Vercel AI SDK](https://composio.dev/toolkits/brex/framework/ai-sdk)
- [LlamaIndex](https://composio.dev/toolkits/brex/framework/llama-index)
- [CrewAI](https://composio.dev/toolkits/brex/framework/crew-ai)

## 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 Brex tools
- Connect Mastra's MCP client to the Composio generated MCP URL
- Fetch Brex 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 Brex 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 Brex MCP server, and what's possible with it?

The Brex MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Brex account. It provides structured and secure access to your company's financial tools, so your agent can perform actions like managing cards, tracking expenses, creating budgets, and retrieving account details on your behalf.
- Card creation and management: Instantly issue new cards, assign them to users or vendors, and control spending limits via your agent.
- Automated expense tracking: Let your agent create and log expenses, helping you keep company finances organized and up to date.
- Budget and department setup: Quickly create budgets for teams or projects and set up new departments without manual effort.
- Account and statement retrieval: Fetch detailed account information and download statements whenever you need financial insights or records.
- User and location management: Add new users or locations to your Brex account, making it easy to scale as your business grows.

## Supported Tools

| Tool slug | Name | Description |
|---|---|---|
| `BREX_CREATE_BUDGET` | Create Budget | Create a new budget for departments or projects. |
| `BREX_CREATE_CARD` | Create Card | Create a new card and assign it to a user. |
| `BREX_CREATE_DEPARTMENT` | Create Department | Create a new department. |
| `BREX_CREATE_EXPENSE` | Create Expense | Create a new expense. |
| `BREX_CREATE_LOCATION` | Create Location | Create a new location. |
| `BREX_CREATE_TITLE` | Create Job Title | Create a new job title. |
| `BREX_CREATE_USER` | Create User | Create a new user in the brex account. |
| `BREX_CREATE_VENDOR_CARD` | Create Vendor Card | Create a new vendor card. |
| `BREX_GET_ACCOUNT_DETAILS` | Get Account Details | Get details about the current brex account. |
| `BREX_GET_ACCOUNT_STATEMENTS` | Get Account Statements | Get account statements. |
| `BREX_GET_BUDGET_DETAILS` | Get Budget Details | Get detailed information about a specific budget. |
| `BREX_GET_BUDGET_TRANSACTIONS` | Get Budget Transactions | Get transactions for a specific budget. |
| `BREX_GET_CARD_DETAILS` | Get Card Details | Get detailed information about a specific card. |
| `BREX_GET_CARD_TRANSACTIONS` | Get Card Transactions | Get card transactions for a date range. |
| `BREX_GET_COMPANY_CASH_ACCOUNTS` | Get Company Cash Accounts | Get company cash accounts. |
| `BREX_GET_EXPENSE_DETAILS` | Get Expense Details | Get details of a specific expense. |
| `BREX_GET_EXPENSES` | Get Expenses | Get expenses for a date range. |
| `BREX_GET_SPEND_LIMITS` | Get Spend Limits | Get spend limits configuration. |
| `BREX_GET_TRANSACTION_BY_ID` | Get Transaction by ID | Get details of a specific transaction by id. |
| `BREX_GET_TRANSACTIONS` | Get Transactions | Get transactions for a date range. |
| `BREX_GET_TRANSACTIONS_BY_AMOUNT_RANGE` | Get Transactions by Amount Range | Get transactions filtered by amount range. |
| `BREX_GET_TRANSACTIONS_BY_DESCRIPTION` | Get Transactions by Description | Get transactions filtered by description text. |
| `BREX_GET_USER_PROFILE` | Get User Profile | Get user profile information for current or specified user. |
| `BREX_LIST_BUDGETS` | List Budgets | List all budgets and show available amounts across all cards. |
| `BREX_LIST_CARDS` | List Cards | List all cards associated with the account. |
| `BREX_LIST_DEPARTMENTS` | List Departments | List all departments in the organization. |
| `BREX_LIST_LOCATIONS` | List Locations | List all locations in the organization. |
| `BREX_LIST_TITLES` | List Job Titles | List all job titles in the organization. |
| `BREX_LIST_USERS` | List Users | List all users in the brex account. |
| `BREX_LIST_VENDORS` | List Vendors | List all vendors. |
| `BREX_TRANSFER_CARD` | Transfer Card | Transfer a card to a different user. |
| `BREX_UPDATE_BUDGET` | Update Budget | Update budget details. |
| `BREX_UPDATE_CARD_LIMITS` | Update Card Limits | Update spending limits and controls for a card. |
| `BREX_UPDATE_CARD_STATUS` | Update Card Status | Update the status of a card (activate/deactivate/terminate). |
| `BREX_UPDATE_USER` | Update User | Update user details. |

## Supported Triggers

None listed.

## Creating MCP Server - Stand-alone vs Composio SDK

The Brex MCP server is an implementation of the Model Context Protocol that connects your AI agent to Brex. It provides structured and secure access so your agent can perform Brex operations on your behalf through a secure, permission-based interface.
With Composio's managed implementation, you don't have to create your own developer app. For production, if you're building an end product, we recommend using your own credentials. The managed server helps you prototype fast and go from 0-1 faster.

## Step-by-step Guide

### 1. 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

### 1. Getting API Keys for OpenAI and Composio

OpenAI API Key
- Go to the [OpenAI dashboard](https://platform.openai.com/settings/organization/api-keys) 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](https://dashboard.composio.dev?utm_source=toolkits&utm_medium=framework_docs).
- Go to Settings and copy your API key.
- This key lets your Mastra agent talk to Composio and reach Brex through MCP.

### 2. Install dependencies

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

### 3. Set up environment variables

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
```bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key_here
```

### 4. Import libraries and validate environment

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
```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,
});
```

### 5. Create a Tool Router session for Brex

What's happening:
- create spins up a short-lived MCP HTTP endpoint for this user
- The toolkits array contains "brex" for Brex access
- session.mcp.url is the MCP URL that Mastra's MCPClient will connect to
```typescript
async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["brex"],
    },
  );

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

### 6. Configure Mastra MCP client and fetch tools

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 Brex toolkit
```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);
```

### 7. Create the Mastra agent

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

### 8. Set up interactive chat interface

What's happening:
- messages keeps the full conversation history in Mastra's expected format
- agent.generate runs the agent with conversation history and Brex 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
```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: {
        brex: 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);
});
```

## Complete Code

```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: ["brex"],
  });

  const composioMCPUrl = session.mcp.url;

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

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "brex-mastra-agent",
    instructions: "You are an AI agent with Brex 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: { brex: 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 Brex 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

## How to build Brex MCP Agent with another framework

- [OpenAI Agents SDK](https://composio.dev/toolkits/brex/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/brex/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/brex/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/brex/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/brex/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/brex/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/brex/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/brex/framework/cli)
- [Google ADK](https://composio.dev/toolkits/brex/framework/google-adk)
- [LangChain](https://composio.dev/toolkits/brex/framework/langchain)
- [Vercel AI SDK](https://composio.dev/toolkits/brex/framework/ai-sdk)
- [LlamaIndex](https://composio.dev/toolkits/brex/framework/llama-index)
- [CrewAI](https://composio.dev/toolkits/brex/framework/crew-ai)

## Related Toolkits

- [Stripe](https://composio.dev/toolkits/stripe) - Stripe is a global online payments platform offering APIs for managing payments, customers, and subscriptions. Trusted by businesses for secure, efficient, and scalable payment processing worldwide.
- [Alpha vantage](https://composio.dev/toolkits/alpha_vantage) - Alpha Vantage is a financial data platform offering real-time and historical stock market APIs. Get instant, reliable access to equities, forex, and technical analysis data for smarter trading decisions.
- [Altoviz](https://composio.dev/toolkits/altoviz) - Altoviz is a cloud-based billing and invoicing platform for businesses. It streamlines online payments, expense tracking, and customizable invoice management.
- [Benzinga](https://composio.dev/toolkits/benzinga) - Benzinga provides real-time financial news and data APIs for market coverage. It helps you track breaking news and actionable market insights instantly.
- [Chaser](https://composio.dev/toolkits/chaser) - Chaser is accounts receivable automation software that sends invoice reminders and helps businesses get paid faster. It streamlines the collections process to save time and improve cash flow.
- [Clientary](https://composio.dev/toolkits/clientary) - Clientary is a platform for managing clients, invoices, projects, proposals, and more. It streamlines client work and saves you serious admin time.
- [Coinbase](https://composio.dev/toolkits/coinbase) - Coinbase is a platform for buying, selling, and storing cryptocurrency. It makes exchanging and managing crypto simple and secure for everyone.
- [Coinranking](https://composio.dev/toolkits/coinranking) - Coinranking is a comprehensive cryptocurrency market data platform offering access to real-time coin prices, market caps, and historical data. Get accurate, up-to-date stats for thousands of digital assets in one place.
- [Coupa](https://composio.dev/toolkits/coupa) - Coupa is a business spend management platform for procurement, invoicing, and expenses. It helps organizations streamline purchasing, control costs, and gain complete visibility over financial operations.
- [CurrencyScoop](https://composio.dev/toolkits/currencyscoop) - CurrencyScoop is a developer-friendly API for real-time and historical currency exchange rates. Easily access fiat and crypto data for smart, up-to-date financial applications.
- [Daffy](https://composio.dev/toolkits/daffy) - Daffy is a modern charitable giving platform with a donor-advised fund. Easily set aside funds, grow them tax-free, and donate to over 1.7 million U.S. charities.
- [Eagle doc](https://composio.dev/toolkits/eagle_doc) - Eagle doc is an AI-powered OCR API for invoices and receipts. It delivers fast, reliable, and accurate document data extraction for seamless automation.
- [Elorus](https://composio.dev/toolkits/elorus) - Elorus is an online invoicing and time-tracking software for freelancers and small businesses. Easily manage finances, bill clients, and track work in one place.
- [Eodhd apis](https://composio.dev/toolkits/eodhd_apis) - Eodhd apis delivers comprehensive financial data, including live and historical stock prices, via robust APIs. Easily access reliable, up-to-date market insights to power your apps, dashboards, and analytics.
- [Fidel api](https://composio.dev/toolkits/fidel_api) - Fidel api is a secure platform for linking payment cards to web and mobile apps. It enables real-time card transaction monitoring and event-based automation for businesses.
- [Finage](https://composio.dev/toolkits/finage) - Finage is a secure API platform delivering real-time and historical financial data for stocks, forex, crypto, indices, and commodities. It empowers developers and businesses to access, analyze, and act on market data instantly.
- [Finmei](https://composio.dev/toolkits/finmei) - Finmei is an invoicing tool that simplifies billing, invoice management, and expense tracking. Ideal for automating and organizing your business finances in one place.
- [Fixer](https://composio.dev/toolkits/fixer) - Fixer is a currency data API offering real-time and historical exchange rates for 170 currencies. Instantly access accurate, up-to-date forex data for your applications and workflows.
- [Fixer io](https://composio.dev/toolkits/fixer_io) - Fixer.io is a lightweight API for real-time and historical foreign exchange rates. It makes global currency conversion fast, accurate, and hassle-free.
- [Flutterwave](https://composio.dev/toolkits/flutterwave) - Flutterwave is a global payments platform enabling businesses to accept and send payments across Africa and beyond. Its robust APIs simplify cross-border transactions and financial operations.

## Frequently Asked Questions

### What are the differences in Tool Router MCP and Brex MCP?

With a standalone Brex MCP server, the agents and LLMs can only access a fixed set of Brex tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Brex and many other apps based on the task at hand, all through a single MCP endpoint.

### Can I use Tool Router MCP with Mastra AI?

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 Brex tools.

### Can I manage the permissions and scopes for Brex while using Tool Router?

Yes, absolutely. You can configure which Brex 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.

### How safe is my data with Composio Tool Router?

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 Brex data and credentials are handled as safely as possible.

---
[See all toolkits](https://composio.dev/toolkits) · [Composio docs](https://docs.composio.dev/llms.txt)