Brex MCP Server

The Brex MCP Server is the official, Brex-operated remote server for the Model Context Protocol. Hosted at https://api.brex.com/mcp, it enables compatible AI clients such as Claude, Claude Desktop, Cursor, or Codex to interact directly with a Brex company account. According to the provider, the server is currently in beta, and the available toolset may change as development continues.

What the Brex MCP Server Covers

The server provides an extensive set of tools aligned with the typical financial operations of a business. According to the official developer documentation at developer.brex.com/docs/mcp, the current toolset spans the following areas:

User management: Query the current user, search for people by name or email, and list cost centers, departments, locations, legal entities, titles, and roles across the company.

Expenses and receipts: Filter expenses by various parameters, retrieve individual expenses by ID, analyze high-level company spend (admins only), update memos on multiple expenses in bulk, upload receipts from URLs, replace attendees for card expenses, and assign card expenses to spend limits.

Cards and limits: List cards with comprehensive filtering, retrieve a specific card by ID, and view all spend limits that apply to the authenticated user.

Banking and transactions: List business bank accounts, retrieve account details, and view banking transactions with filtering.

Bills and vendors: Filter bills, retrieve individual bills by ID, view vendor details, and list all company vendors.

Travel: List business trips with filtering and pagination, view bookings, and manage group events such as offsites or conferences.

Accounting integration: Retrieve the active accounting integration, view accounting records, and list general ledger accounts.

Miscellaneous: Check reward points and redemption eligibility, list merchants and expense categories, and submit feedback directly to the Brex product team.

Access, Permissions, and Beta Prerequisites

According to the provider, using the MCP server requires two steps performed by an account or card admin: accepting the Developer API agreement under Settings → Developer, and enabling beta access under Settings → Beta features → Brex in AI Assistants. Once done, all users in the company account can connect with their own credentials via OAuth.

Each tool is tied to the individual user's Brex capability. A user with general access can query their own expenses and user lists, but analyzing company-wide spend requires account or card admin status. Actions such as approvals and card management are currently not available via MCP, per the provider.

Connecting: OAuth and API Keys

The recommended approach is OAuth. MCP clients that support OAuth automatically initiate a browser-based authorization flow on first connection, with no manual token setup. The authorization server is at https://accounts-api.brex.com/oauth2/default, and the server supports Dynamic Client Registration (RFC 7591), so clients do not need to be pre-registered. Sessions remain active, so repeated authorization is not required.

For clients without OAuth support, or for programmatic access, account and card admins can generate a Brex API token and pass it as a Bearer token in the Authorization header. The documentation recommends creating tokens with minimal scopes, using the client's secret management features, and never storing tokens in repositories or shared configuration files.

Integration with Common AI Clients

For Claude Code, a single command suffices: claude mcp add --transport http brex https://api.brex.com/mcp. Claude Desktop supports adding the server through the Claude connectors catalog or manually via JSON configuration. Cursor uses Settings → MCP with type http and the server URL. Codex uses codex mcp add brex --url https://api.brex.com/mcp. Any client that supports MCP HTTP transport can connect directly.

Security Considerations and Data Path

The Brex MCP Server accesses financially sensitive company data, including expenses, card details, banking transactions, and vendors. This creates several important security considerations:

First, every tool response leaves Brex and travels to the connected AI client and its model provider. Prompts, tool calls, and results may appear in the client's logs, retention path, or model policy. Brex privacy terms, client policies, and model provider terms all apply simultaneously.

Second, for AI assistants capable of executing actions — such as updating memos, uploading receipts, or assigning expenses to limits — enabling human confirmation before actions is strongly recommended to prevent unintended writes.

Third, Brex recommends monitoring API logs in the dashboard to track MCP activity, and revoking sessions under Settings → Personal settings → Connected integrations if unexpected behavior occurs.

Since there is no public source repository, no GitHub star count is available. Brex operates the MCP Server as a hosted remote service with no published source code.

FAQ

Can everyone in the company use the MCP Server? Yes, once an admin has enabled the beta, all account users can connect with their own credentials. Permissions follow individual Brex roles.

Are write actions possible? Yes, for some operations: updating memos, uploading receipts, replacing attendees, and assigning expenses to limits. Approvals and card management are not yet available per the provider.

How do I set up the server? An admin must accept the Developer API agreement and enable beta access. After that, Claude Code requires a single command; other clients require manual URL configuration.