Brex MCP Server

Brex MCP Server

A Model Context Protocol (MCP) server for the Brex API. Optimized for safe, small, read-only responses with projection and batching.

Quick Start

1. Install and build

2. Run with stdio (example)

3. Configure your MCP client to launch this command and pass env vars:

• BREX_API_KEY (required)
• BREX_API_URL default https://platform.brexapis.com

Resources

• brex://expenses | brex://expenses/{id} | brex://expenses/card | brex://expenses/card/{id}
• brex://budgets | brex://budgets/{id}
• brex://spend_limits | brex://spend_limits/{id}
• brex://budget_programs | brex://budget_programs/{id}
• brex://transactions/card/primary | brex://transactions/cash/{id}
• brex://docs/usage (compact usage guide for agents)

Notes:

• Resources accept ?summary_only=true&fields=id,status,... to control payload size.
• Expenses resources auto-expand merchant and budget for readability.

Tools (read-only unless noted)

• Budgets: get_budgets, get_budget
• Spend Limits: get_spend_limits, get_spend_limit
• Budget Programs: get_budget_programs, get_budget_program
• Expenses (single page): get_expenses
• Expenses (paginated): get_all_expenses, get_all_card_expenses
• Expense by ID: get_expense, get_card_expense
• Card Statements: get_card_statements_primary
• Transactions: get_card_transactions, get_cash_transactions
• Cash Statements: get_cash_account_statements
• Accounts: get_all_accounts, get_account_details
• Receipts (write): match_receipt, upload_receipt
• Updates (write): update_expense

How to call tools

Always send parameters under arguments (not input). Keep payloads small with summary_only and fields.

Common parameters:

• summary_only: boolean — compact projection; server auto-falls back if >24k tokens
• fields: string[] — dot-notation projection (e.g., purchased_amount.amount)
• Pagination: page_size (<=50), max_items (<=500 recommended)
• Date batching: start_date, end_date, window_days
• Thresholds: min_amount, max_amount

Recommended examples:

Best practices:

• Always include summary_only: true and a focused fields list.
• Use date ranges and window_days for high-volume orgs.
• Keep page_size <= 50, prefer small max_items.
• Cash endpoints require additional Brex scopes; handle 403s gracefully.

Publishing

Only build/, README.md, and LICENSE are published.

License

MIT — see LICENSE.