# How to integrate Brex MCP with Pydantic AI ```json { "title": "How to integrate Brex MCP with Pydantic AI", "toolkit": "Brex", "toolkit_slug": "brex", "framework": "Pydantic AI", "framework_slug": "pydantic-ai", "url": "https://composio.dev/toolkits/brex/framework/pydantic-ai", "markdown_url": "https://composio.dev/toolkits/brex/framework/pydantic-ai.md", "updated_at": "2026-05-06T08:03:57.847Z" } ``` ## Introduction This guide walks you through connecting Brex to Pydantic 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 Pydantic 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) - [Mastra AI](https://composio.dev/toolkits/brex/framework/mastra-ai) - [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: - How to set up your Composio API key and User ID - How to create a Composio Tool Router session for Brex - How to attach an MCP Server to a Pydantic AI agent - How to stream responses and maintain chat history - How to build a simple REPL-style chat interface to test your Brex workflows ## What is Pydantic AI? Pydantic AI is a Python framework for building AI agents with strong typing and validation. It leverages Pydantic's data validation capabilities to create robust, type-safe AI applications. Key features include: - Type Safety: Built on Pydantic for automatic data validation - MCP Support: Native support for Model Context Protocol servers - Streaming: Built-in support for streaming responses - Async First: Designed for async/await patterns ## 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: - Python 3.9 or higher - A Composio account with an active API key - Basic familiarity with Python and async programming ### 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'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](https://dashboard.composio.dev?utm_source=toolkits&utm_medium=framework_docs). - Navigate to your API settings and generate a new API key. - Store this key securely as you'll need it for authentication. ### 2. Install dependencies Install the required libraries. What's happening: - composio connects your agent to external SaaS tools like Brex - pydantic-ai lets you create structured AI agents with tool support - python-dotenv loads your environment variables securely from a .env file ```bash pip install composio pydantic-ai python-dotenv ``` ### 3. Set up environment variables Create a .env file in your project root. What's happening: - COMPOSIO_API_KEY authenticates your agent to Composio's API - USER_ID associates your session with your account for secure tool access - OPENAI_API_KEY to access OpenAI LLMs ```bash COMPOSIO_API_KEY=your_composio_api_key_here USER_ID=your_user_id_here OPENAI_API_KEY=your_openai_api_key ``` ### 4. Import dependencies What's happening: - We load environment variables and import required modules - Composio manages connections to Brex - MCPServerStreamableHTTP connects to the Brex MCP server endpoint - Agent from Pydantic AI lets you define and run the AI assistant ```python import asyncio import os from dotenv import load_dotenv from composio import Composio from pydantic_ai import Agent from pydantic_ai.mcp import MCPServerStreamableHTTP load_dotenv() ``` ### 5. Create a Tool Router Session What's happening: - We're creating a Tool Router session that gives your agent access to Brex 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 ```python async def main(): api_key = os.getenv("COMPOSIO_API_KEY") user_id = os.getenv("USER_ID") if not api_key or not user_id: raise RuntimeError("Set COMPOSIO_API_KEY and USER_ID in your environment") # Create a Composio Tool Router session for Brex composio = Composio(api_key=api_key) session = composio.create( user_id=user_id, toolkits=["brex"], ) url = session.mcp.url if not url: raise ValueError("Composio session did not return an MCP URL") ``` ### 6. Initialize the Pydantic AI Agent What's happening: - The MCP client connects to the Brex endpoint - The agent uses GPT-5 to interpret user commands and perform Brex operations - The instructions field defines the agent's role and behavior ```python # Attach the MCP server to a Pydantic AI Agent brex_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY}) agent = Agent( "openai:gpt-5", toolsets=[brex_mcp], instructions=( "You are a Brex assistant. Use Brex tools to help users " "with their requests. Ask clarifying questions when needed." ), ) ``` ### 7. Build the chat interface What's happening: - The agent reads input from the terminal and streams its response - Brex API calls happen automatically under the hood - The model keeps conversation history to maintain context across turns ```python # Simple REPL with message history history = [] print("Chat started! Type 'exit' or 'quit' to end.\n") print("Try asking the agent to help you with Brex.\n") while True: user_input = input("You: ").strip() if user_input.lower() in {"exit", "quit", "bye"}: print("\nGoodbye!") break if not user_input: continue print("\nAgent is thinking...\n", flush=True) async with agent.run_stream(user_input, message_history=history) as stream_result: collected_text = "" async for chunk in stream_result.stream_output(): text_piece = None if isinstance(chunk, str): text_piece = chunk elif hasattr(chunk, "delta") and isinstance(chunk.delta, str): text_piece = chunk.delta elif hasattr(chunk, "text"): text_piece = chunk.text if text_piece: collected_text += text_piece result = stream_result print(f"Agent: {collected_text}\n") history = result.all_messages() ``` ### 8. Run the application What's happening: - The asyncio loop launches the agent and keeps it running until you exit ```python if __name__ == "__main__": asyncio.run(main()) ``` ## Complete Code ```python import asyncio import os from dotenv import load_dotenv from composio import Composio from pydantic_ai import Agent from pydantic_ai.mcp import MCPServerStreamableHTTP load_dotenv() async def main(): api_key = os.getenv("COMPOSIO_API_KEY") user_id = os.getenv("USER_ID") if not api_key or not user_id: raise RuntimeError("Set COMPOSIO_API_KEY and USER_ID in your environment") # Create a Composio Tool Router session for Brex composio = Composio(api_key=api_key) session = composio.create( user_id=user_id, toolkits=["brex"], ) url = session.mcp.url if not url: raise ValueError("Composio session did not return an MCP URL") # Attach the MCP server to a Pydantic AI Agent brex_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY}) agent = Agent( "openai:gpt-5", toolsets=[brex_mcp], instructions=( "You are a Brex assistant. Use Brex tools to help users " "with their requests. Ask clarifying questions when needed." ), ) # Simple REPL with message history history = [] print("Chat started! Type 'exit' or 'quit' to end.\n") print("Try asking the agent to help you with Brex.\n") while True: user_input = input("You: ").strip() if user_input.lower() in {"exit", "quit", "bye"}: print("\nGoodbye!") break if not user_input: continue print("\nAgent is thinking...\n", flush=True) async with agent.run_stream(user_input, message_history=history) as stream_result: collected_text = "" async for chunk in stream_result.stream_output(): text_piece = None if isinstance(chunk, str): text_piece = chunk elif hasattr(chunk, "delta") and isinstance(chunk.delta, str): text_piece = chunk.delta elif hasattr(chunk, "text"): text_piece = chunk.text if text_piece: collected_text += text_piece result = stream_result print(f"Agent: {collected_text}\n") history = result.all_messages() if __name__ == "__main__": asyncio.run(main()) ``` ## Conclusion You've built a Pydantic AI agent that can interact with Brex through Composio's Tool Router. With this setup, your agent can perform real Brex actions through natural language. You can extend this further by: - Adding other toolkits like Gmail, HubSpot, or Salesforce - Building a web-based chat interface around this agent - Using multiple MCP endpoints to enable cross-app workflows (for example, Gmail + Brex for workflow automation) This architecture makes your AI agent "agent-native", able to securely use APIs in a unified, composable way without custom integrations. ## 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) - [Mastra AI](https://composio.dev/toolkits/brex/framework/mastra-ai) - [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 Pydantic AI? Yes, you can. Pydantic 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) ยท [Composio docs](https://docs.composio.dev/llms.txt)