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How to integrate Brex MCP with Google ADK

Connect Google ADK to Brex MCP. Create a new card for our intern, get the latest account statement pdf, and more using natural language, with authentication handled for you.

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Brex provides corporate credit cards and spend management tailored for startups and tech businesses. It helps optimize company cash flow, streamline accounting, and accelerate business growth.

84 Tools

Introduction

This guide walks you through connecting Brex to Google ADK using the Composio tool router. By the end, you'll have a working Brex agent that can track card transactions and expenses, manage cards and spend limits, create budgets, and manage users and vendors through natural language commands.

This guide will help you understand how to give your Google ADK 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

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TL;DR

Here's what you'll learn:
  • Get a Brex account set up and connected to Composio
  • Install the Google ADK and Composio packages
  • Create a Composio Tool Router session for Brex
  • Build an agent that connects to Brex through MCP
  • Interact with Brex using natural language

What is Google ADK?

Google ADK (Agents Development Kit) is Google's framework for building AI agents powered by Gemini models. It provides tools for creating agents that can use external services through the Model Context Protocol.

Key features include:

  • Gemini Integration: Native support for Google's Gemini models
  • MCP Toolset: Built-in support for Model Context Protocol tools
  • Streamable HTTP: Connect to external services through streamable HTTP
  • CLI and Web UI: Run agents via command line or web interface

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, 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.

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 step09 STEPS
1

Prerequisites

Before starting, make sure you have:
  • A Google API key for Gemini models
  • A Composio account and API key
  • Python 3.9 or later installed
  • Basic familiarity with Python
2

Getting API Keys for Google and Composio

Google API Key
  • Go to Google AI Studio and create an API key.
  • Copy the key and keep it safe. You will put this in GOOGLE_API_KEY.
Composio API Key and User ID
  • Log in to the Composio dashboard.
  • Go to Settings → API Keys and copy your Composio API key. Use this for COMPOSIO_API_KEY.
  • Decide on a stable user identifier to scope sessions, often your email or a user ID. Use this for COMPOSIO_USER_ID.
3

Install dependencies

bash
pip install google-adk composio python-dotenv

Inside your virtual environment, install the required packages.

What's happening:

  • google-adk is Google's Agents Development Kit
  • composio connects your agent to Brex via MCP
  • python-dotenv loads environment variables
4

Set up ADK project

bash
adk create my_agent

Set up a new Google ADK project.

What's happening:

  • This creates an agent folder with a root agent file and .env file
5

Set environment variables

bash
GOOGLE_API_KEY=your-google-api-key
COMPOSIO_API_KEY=your-composio-api-key
COMPOSIO_USER_ID=your-user-id-or-email

Save all your credentials in the .env file.

What's happening:

  • GOOGLE_API_KEY authenticates with Google's Gemini models
  • COMPOSIO_API_KEY authenticates with Composio
  • COMPOSIO_USER_ID identifies the user for session management
6

Import modules and validate environment

python
import os
import warnings

from composio import Composio
from dotenv import load_dotenv
from google.adk.agents.llm_agent import Agent
from google.adk.tools.mcp_tool.mcp_session_manager import StreamableHTTPConnectionParams
from google.adk.tools.mcp_tool.mcp_toolset import McpToolset

load_dotenv()

warnings.filterwarnings("ignore", message=".*BaseAuthenticatedTool.*")

GOOGLE_API_KEY = os.getenv("GOOGLE_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not GOOGLE_API_KEY:
    raise ValueError("GOOGLE_API_KEY is not set in the environment.")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set in the environment.")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set in the environment.")
What's happening:
  • os reads environment variables
  • Composio is the main Composio SDK client
  • GoogleProvider declares that you are using Google ADK as the agent runtime
  • Agent is the Google ADK LLM agent class
  • McpToolset lets the ADK agent call MCP tools over HTTP
7

Create Composio client and Tool Router session

python
composio_client = Composio(api_key=COMPOSIO_API_KEY)

composio_session = composio_client.create(
    user_id=COMPOSIO_USER_ID,
    toolkits=["brex"],
)

COMPOSIO_MCP_URL = composio_session.mcp.url,
print(f"Composio MCP URL: {COMPOSIO_MCP_URL}")
What's happening:
  • Authenticates to Composio with your API key
  • Declares Google ADK as the provider
  • Spins up a short-lived MCP endpoint for your user and selected toolkit
  • Stores the MCP HTTP URL for the ADK MCP integration
8

Set up the McpToolset and create the Agent

python
composio_toolset = McpToolset(
    connection_params=StreamableHTTPConnectionParams(
        url=COMPOSIO_MCP_URL,
        headers={"x-api-key": COMPOSIO_API_KEY}
    )
)

root_agent = Agent(
    model="gemini-2.5-flash",
    name="composio_agent",
    description="An agent that uses Composio tools to perform actions.",
    instruction=(
        "You are a helpful assistant connected to Composio. "
        "You have the following tools available: "
        "COMPOSIO_SEARCH_TOOLS, COMPOSIO_MULTI_EXECUTE_TOOL, "
        "COMPOSIO_MANAGE_CONNECTIONS, COMPOSIO_REMOTE_BASH_TOOL, COMPOSIO_REMOTE_WORKBENCH. "
        "Use these tools to help users with Brex operations."
    ),
    tools=[composio_toolset],
)

print("\nAgent setup complete. You can now run this agent directly ;)")
What's happening:
  • Connects the ADK agent to the Composio MCP endpoint through McpToolset
  • Uses Gemini as the model powering the agent
  • Lists exact tool names in instruction to reduce misnamed tool calls
9

Run the agent

bash
# Run in CLI mode
adk run my_agent

# Or run in web UI mode
adk web

Execute the agent from the project root. The web command opens a web portal where you can chat with the agent.

What's happening:

  • adk run runs the agent in CLI mode
  • adk web . opens a web UI for interactive testing

Complete Code

Here's the complete code to get you started with Brex and Google ADK:

python
import os
import warnings

from composio import Composio
from composio_google import GoogleProvider
from dotenv import load_dotenv
from google.adk.agents.llm_agent import Agent
from google.adk.tools.mcp_tool.mcp_session_manager import StreamableHTTPConnectionParams
from google.adk.tools.mcp_tool.mcp_toolset import McpToolset

load_dotenv()
warnings.filterwarnings("ignore", message=".*BaseAuthenticatedTool.*")

GOOGLE_API_KEY = os.getenv("GOOGLE_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not GOOGLE_API_KEY:
    raise ValueError("GOOGLE_API_KEY is not set in the environment.")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set in the environment.")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set in the environment.")

composio_client = Composio(api_key=COMPOSIO_API_KEY, provider=GoogleProvider())

composio_session = composio_client.create(
    user_id=COMPOSIO_USER_ID,
    toolkits=["brex"],
)

COMPOSIO_MCP_URL = composio_session.mcp.url


composio_toolset = McpToolset(
    connection_params=StreamableHTTPConnectionParams(
        url=COMPOSIO_MCP_URL,
        headers={"x-api-key": COMPOSIO_API_KEY}
    )
)

root_agent = Agent(
    model="gemini-2.5-flash",
    name="composio_agent",
    description="An agent that uses Composio tools to perform actions.",
    instruction=(
        "You are a helpful assistant connected to Composio. "
        "You have the following tools available: "
        "COMPOSIO_SEARCH_TOOLS, COMPOSIO_MULTI_EXECUTE_TOOL, "
        "COMPOSIO_MANAGE_CONNECTIONS, COMPOSIO_REMOTE_BASH_TOOL, COMPOSIO_REMOTE_WORKBENCH. "
        "Use these tools to help users with Brex operations."
    ),  
    tools=[composio_toolset],
)

print("\nAgent setup complete. You can now run this agent directly ;)")

Conclusion

You've successfully integrated Brex with the Google ADK through Composio's MCP Tool Router. Your agent can now interact with Brex using natural language commands.

Key takeaways:

  • The Tool Router approach dynamically routes requests to the appropriate Brex tools
  • Environment variables keep your credentials secure and separate from code
  • Clear agent instructions reduce tool calling errors
  • The ADK web UI provides an interactive interface for testing and development

You can extend this setup by adding more toolkits to the toolkits array in your session configuration.

TOOLS

Supported Tools

Every Brex action and event your agent gets out of the box.

Add Webhook Group Members

Add webhook subscription members to a webhook group.

Archive Budget

Archive a budget to mark it as inactive and prevent future expenses.

Archive Spend Limit

Archive a spend limit in Brex.

Create Budget

Create a new budget for a department or project under an existing parent budget.

Create Spend Limit (Budget V1)

Tool to create a new Spend Limit (Budget) in Brex.

Create Card

Create a new card and assign it to a user.

Create Department

Create a new department.

Create Document Upload for Referral

Create a document upload URL for a referral and return a pre-signed S3 upload URL.

Create Expense

Create a new expense.

Create Custom Field

Create a new custom field in Brex.

Create Field Values

Create custom field values for a specific Brex field.

Create Location

Create a new location.

Create Referral Request

Tool to create a new referral to Brex for onboarding.

Create Spend Limit

Tool to create a spend limit in Brex.

Create Job Title

Create a new job title.

Create User

Create a new user in the Brex account.

Create Vendor

Create a new vendor in Brex for payment operations.

Create Webhook Group

Tool to create a webhook group for targeting webhook subscriptions.

Create Webhook Subscription

Register a new webhook subscription to receive real-time notifications for Brex events.

Delete Field

Tool to delete a custom field by Brex ID.

Delete Field Values

Delete custom field values for a specific field.

Delete Vendor

Delete a vendor by ID.

Get Account Statements

Get finalized statements for the primary cash account.

Get Budget Details

Get detailed information about a specific budget.

Get Card Details

Get detailed information about a specific card.

Get Card Expense

Tool to retrieve detailed information about a specific card expense by its ID.

Get Card Number

Get card number, CVV, and expiration date for a specific card.

Get Card Transactions

Get settled card transactions for the primary card account.

Get Company Cash Accounts

Retrieve company cash (deposit) accounts one page at a time, including balances, account numbers, routing numbers, and status.

Get Company Details

Get company information associated with the OAuth2 access token.

Get Department By ID

Get detailed information about a specific department by ID.

Get Expense

Tool to get details of a specific expense by ID.

Get Field By ID

Tool to retrieve a custom field by its Brex ID.

Get Field Value By ID

Retrieve a custom field value by its parent field ID and the value's Brex ID.

Get Legal Entity

Tool to retrieve a legal entity by its ID from Brex.

Get Location By ID

Get detailed information about a specific location by ID.

Get Referral By ID

Tool to retrieve a specific referral by its ID from Brex.

Get Spend Limit By ID

Tool to get detailed information about a specific spend limit by its ID.

Get Spend Limits

Get spend limits configuration for the account.

Get Title by ID

Get detailed information about a specific job title by ID.

Get Transaction by ID

Get a card transaction by ID by searching up to 10 pages of transactions from the primary account.

Get Card Transactions

Get settled card transactions from the primary Brex account, with optional client-side posted-date filtering.

Get Transactions by Amount Range

Find primary-account card transactions within an inclusive USD amount range and posted-date range.

Search Transactions by Description

Search and filter card transactions by description text.

Get User Limit

Retrieves the monthly spending limit and available balance for a specific Brex user.

Get User Profile

Get user profile information from Brex Team API.

Get Vendor By ID

Tool to get vendor details by ID.

Get Webhook Group

Tool to retrieve details of a specific webhook group by ID.

Get Webhook Subscription

Tool to retrieve details of a specific webhook subscription by ID.

List Budget Programs

Tool to list all budget programs in the organization.

List Budgets

List a page of budgets and calculate an available-budget summary from the returned budgets.

List Card Accounts

Tool to list all card accounts for the company.

List Cards

List cards associated with the account, returning one page at a time.

List Card Statements

Tool to list finalized statements for primary card accounts.

List Departments

List departments in the organization one page at a time.

List Expenses

Tool to list expenses from the Brex platform.

List Field Values

List a page of values under a custom field, optionally filtering by Brex ID, value ID, remote ID, or value string.

List Legal Entities

Tool to list all legal entities in the Brex account with pagination support.

List Locations

List locations in the organization, one page at a time.

List Referrals

Tool to list all referrals created in the Brex account.

List Job Titles

List job titles in the organization, one page at a time, using a cursor to retrieve subsequent pages.

List Transfers

Lists transfers for the account.

List Trips

Lists trips according to the filters passed in the query string.

List Users

List users in the Brex account, one page at a time using a limit and pagination cursor.

List Vendors

List vendors in Brex, one page at a time using a limit and pagination cursor.

List Webhook Group Members

Tool to list all members of a webhook group.

List Webhook Groups

Tool to list all webhook groups.

List Webhook Secrets

Tool to retrieve webhook signing secrets for validating incoming webhook messages from Brex.

List Webhook Subscriptions

Tool to list all registered webhook subscriptions.

Create Receipt Match

Creates a receipt match request and returns a pre-signed S3 upload URI.

Create Receipt Upload for Expense

Creates a receipt upload request for a specific card expense and returns a pre-signed S3 upload URL.

Set User Limit

Set or update a Brex user's monthly spending limit, with amounts in the smallest currency unit.

Transfer Card

Transfer a card to a different user.

Update Budget

Update an existing budget's configuration in Brex.

Update Spend Limit (V1)

Tool to update a Spend Limit (budget) using the v1 API.

Update Card Limits

Update spending limits and controls for a Brex card.

Update Card Status

Update the status of a Brex card by locking, unlocking, or terminating it.

Update Expense

Update a card expense by ID, modifying one or more of its memo, location, department, or category fields in a single request.

Update Field

Tool to update a custom field in Brex.

Update Field Values

Tool to update custom field values in Brex for a specific field.

Update Spend Limit

Updates an existing Brex spend limit by its ID.

Update User

Update a Brex user's manager, department, location, or title by user ID.

Update Vendor

Tool to update vendor information in Brex.

Update Webhook Subscription

Updates an existing Brex webhook subscription's configuration by ID.

FRAMEWORKS

How to build Brex MCP Agent with another framework

Claude Code logo

Claude Code

Use Brex MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Brex MCP with Claude Cowork

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Brex MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Brex MCP with Claude Agent SDK

Codex logo

Codex

Use Brex MCP with Codex

OpenClaw logo

OpenClaw

Use Brex MCP with OpenClaw

Hermes logo

Hermes

Use Brex MCP with Hermes

Atomic Agent logo

Atomic Agent

Use Brex MCP with Atomic Agent

LangChain logo

LangChain

Use Brex MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Brex MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Brex MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Brex MCP with LlamaIndex

CrewAI logo

CrewAI

Use Brex MCP with CrewAI

Pydantic AI logo

Pydantic AI

Use Brex MCP with Pydantic AI

AutoGen logo

AutoGen

Use Brex MCP with AutoGen

FAQ

Frequently asked questions

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.

Yes, you can. Google ADK 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.

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.

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.

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