Brex MCP Server

# Product Requirements Document: MCP Server for Brex API Integration ## Overview The Model Context Protocol (MCP) Server for Brex will provide a secure bridge between LLM applications and Brex financial data. This server will focus exclusively on read-only access to Brex data, exposing it as resources through the MCP interface, while explicitly avoiding any write operations to ensure maximum security. ## Product Vision Enable AI applications to securely access and analyze Brex financial data through a standardized protocol, enhancing financial intelligence without introducing operational risks. ## Target Users - Financial analysts using AI tools - Business intelligence teams - Finance departments leveraging LLMs - Developers building LLM applications that need financial context ## Business Requirements 1. Provide read-only access to Brex financial data 2. Maintain security and privacy of sensitive financial information 3. Comply with financial data handling regulations 4. Support integration with existing LLM workflows 5. Enable financial analytics through AI without requiring direct Brex API access ## Functional Requirements ### Core Functionality 1. **MCP Server Implementation** - Create an MCP-compliant server using the TypeScript SDK - Support both stdio and HTTP/SSE transport layers - Implement proper authentication management for Brex API - Handle rate limiting and error responses 2. **Resources (Read-Only Data)** - Transaction history resources - Budget information - Card and account data - User, department, and location information - Vendor and payment data 3. **Prompts** - Financial analysis templates - Spend pattern recognition - Budget vs. actual reporting - Transaction categorization - Expense trend identification ### Supported Brex API Endpoints (Read-Only) 1. **Transactions API** - List transactions for card accounts - List transactions for cash accounts - Get transaction details 2. **Accounts API** - List card accounts - List cash accounts - Get account details - Get statements 3. **Team API** - List users - List departments - List locations - List cards (without PAN details) 4. **Budgets API** - List budgets - List spend limits - Get budget details 5. **Expenses API** - List expenses - Get expense details ## Resource Schema | Resource Category | Resource URI Pattern | Description | |-------------------|----------------------|-------------| | Transactions | `transactions://card/primary` | Primary card transactions | | Transactions | `transactions://cash/{id}` | Cash account transactions | | Accounts | `accounts://cash/list` | List of cash accounts | | Accounts | `accounts://card/list` | List of card accounts | | Accounts | `accounts://cash/{id}` | Specific cash account details | | Team | `users://list` | List of all users | | Team | `users://{id}` | Specific user details | | Team | `departments://list` | List of departments | | Team | `locations://list` | List of locations | | Cards | `cards://list` | List of cards (excluding sensitive data) | | Cards | `cards://{id}` | Specific card details (excluding sensitive data) | | Budgets | `budgets://list` | List of budgets | | Budgets | `budgets://{id}` | Specific budget details | | Expenses | `expenses://list` | List of expenses | | Expenses | `expenses://{id}` | Specific expense details | ## Technical Requirements 1. **Authentication** - Secure storage and management of Brex API tokens - Support for token refresh when necessary - Proper error handling for authentication failures 2. **Performance** - Respect Brex API rate limits (1,000 requests in 60 seconds) - Implement caching for frequently accessed resources - Optimize payload sizes for efficient transmission 3. **Security** - No storage of credentials in code - TLS for all HTTP communications - Proper error handling to prevent information leakage - Strict read-only access enforcement 4. **Error Handling** - Translate Brex API errors into meaningful MCP responses - Provide detailed logging for troubleshooting - Graceful degradation when services are unavailable ## Integration Requirements 1. **Deployment** - Support for containerized deployment - Configuration through environment variables - Health check endpoints 2. **Monitoring** - Request/response logging - Error rate tracking - Performance metrics 3. **Documentation** - API documentation for all exposed resources - Installation and setup guide - Security best practices ## Constraints 1. **Security Constraints** - No implementation of write operations (tools) - No exposure of sensitive card information (full PAN, CVV) - No storage of Brex credentials in the codebase 2. **Technical Constraints** - Must adhere to MCP specification - Must respect Brex API rate limits - Must handle pagination for large data sets ## Success Metrics 1. **Technical Metrics** - Successful resource retrieval rate (>99%) - API latency (<500ms for most operations) - Error rate (<1% of requests) 2. **Business Metrics** - Reduction in manual financial data retrieval time - Increased usage of financial data in AI workflows - User satisfaction with data accessibility ## Out of Scope 1. **Write Operations** - Creating payments or transfers - Inviting or managing users - Creating or managing cards - Setting spending limits - Creating or modifying budgets 2. **Direct LLM Integration** - The server provides data to LLMs but does not include LLM functionality 3. **Data Analysis** - The server provides raw data but does not perform analysis - Analysis is left to the LLM or client application ## Future Considerations 1. **Enhanced Filtering** - More sophisticated filtering options for transactions and expenses - Date range and category-based filtering 2. **Aggregated Views** - Pre-calculated summaries and aggregations - Custom reporting views 3. **Conditional Access** - Role-based access controls - Data masking for sensitive information 4. **Webhook Integration** - Real-time data updates through webhook subscriptions - Event-driven resource refreshing ## Implementation Timeline 1. **Phase 1 (4 weeks)** - Core MCP server implementation - Authentication handling - Basic transaction and account resources 2. **Phase 2 (4 weeks)** - Team and card resources - Budget and expense resources - Prompt templates 3. **Phase 3 (2 weeks)** - Performance optimization - Caching implementation - Documentation and testing 4. **Phase 4 (2 weeks)** - Deployment and monitoring setup - Final security review - User acceptance testing ## Conclusion The MCP Server for Brex API Integration will provide a secure, read-only bridge between LLM applications and Brex financial data. By focusing exclusively on resource exposure (not tools), the server minimizes security risks while maximizing the value of making financial data accessible to AI workflows.