Brex MCP Server
A Model Context Protocol (MCP) server for the Brex API. Optimized for safe, small, read-only responses with projection and batching.
Installation
Claude Code
# Install the package
npm install -g mcp-brex
# Add to Claude Code with your API key
claude mcp add brex --env BREX_API_KEY=your_brex_api_key -- npx mcp-brex
Claude Desktop
Add to your claude_desktop_config.json:
{
"mcpServers": {
"brex": {
"command": "npx",
"args": ["mcp-brex"],
"env": {
"BREX_API_KEY": "your_brex_api_key"
}
}
}
}
Manual Setup (Development)
git clone https://github.com/dennisonbertram/mcp-brex.git
cd mcp-brex
npm install
npm run build
claude mcp add brex --env BREX_API_KEY=your_key -- node build/index.js
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
merchantandbudgetfor 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 pagination and filtering.
Common parameters:
- Pagination:
page_size(<=50),max_items(<=200 recommended) - Date filtering:
start_date,end_date,window_days - Status filtering:
statusarray for expenses/transactions - Amount filtering:
min_amount,max_amountfor expenses - Merchant filtering:
merchant_namefor expenses - Expand control:
expandarray to include nested objects (e.g.,["merchant", "budget"])
Recommended examples:
{
"name": "get_all_card_expenses",
"arguments": {
"page_size": 10,
"max_items": 20,
"start_date": "2025-08-25T00:00:00Z",
"end_date": "2025-08-26T00:00:00Z",
"status": ["APPROVED"],
"min_amount": 100
}
}
{
"name": "get_expenses",
"arguments": {
"limit": 5,
"status": "APPROVED"
}
}
{
"name": "get_card_transactions",
"arguments": {
"limit": 10,
"posted_at_start": "2025-08-25T00:00:00Z"
}
}
{
"name": "get_all_accounts",
"arguments": {
"page_size": 10,
"max_items": 20,
"status": "ACTIVE"
}
}
{
"name": "get_transactions",
"arguments": {
"accountId": "acc_123456789",
"limit": 10
}
}
{
"name": "get_expenses",
"arguments": {
"limit": 5,
"expand": ["merchant", "user"]
}
}
Pagination and Filtering Best Practices
IMPORTANT: Use pagination, filtering, and sorting to control response sizes instead of relying on summaries.
Key Parameters for Data Control:
page_size: number— Items per page (recommended: ≤50)max_items: number— Maximum total items across all pages (recommended: ≤200)start_date/end_date: string— ISO date range filteringwindow_days: number— Split large date ranges into smaller batchesstatus: string[]— Filter by status (e.g., ["APPROVED", "PENDING"])min_amount/max_amount: number— Amount-based filtering for expenses
Best Practices:
- Always use date ranges for bulk requests to avoid huge responses
- Use small page sizes (≤50) and reasonable max_items (≤200)
- Apply status filters to get only the data you need
- Use window_days (e.g., 7) to batch large date ranges
- Control nested object expansion with the
expandparameter:- Default:
expand: []returns lean objects (~500-1000 tokens each) - With expansion:
expand: ["merchant", "budget"]returns full objects (~15K+ tokens each) - Available expand options:
merchant,budget,user,department,location,receipts
- Default:
- Test with small limits first before scaling up
- Cash endpoints require additional Brex scopes; handle 403s gracefully
Publishing
Only build/, README.md, and LICENSE are published.
License
MIT — see LICENSE.