Brex MCP Server

/** * @file Get Expenses Tool * @version 1.0.0 * @description Implementation of the get_expenses tool for the Brex MCP server */ import { Server } from "@modelcontextprotocol/sdk/server/index.js"; import { BrexClient } from "../services/brex/client.js"; import { logDebug, logError } from "../utils/logger.js"; import { ExpenseType, ExpenseStatus, ExpensePaymentStatus, ListExpensesParams, isExpense } from "../services/brex/expenses-types.js"; import { registerToolHandler, ToolCallRequest } from "./index.js"; // Get Brex client function getBrexClient(): BrexClient { return new BrexClient(); } /** * Interface for get_expenses tool input parameters */ interface GetExpensesParams { expense_type?: ExpenseType; status?: ExpenseStatus; payment_status?: ExpensePaymentStatus; limit?: number; expand?: string[]; } /** * Validates and processes the get_expenses tool parameters * @param input The raw input parameters from the tool call * @returns Validated parameters */ function validateParams(input: any): GetExpensesParams { if (!input) { return {}; // All parameters are optional } const params: GetExpensesParams = {}; // Validate expense_type if provided if (input.expense_type !== undefined) { if (!Object.values(ExpenseType).includes(input.expense_type)) { throw new Error(`Invalid expense_type: ${input.expense_type}`); } params.expense_type = input.expense_type; } // Validate status if provided if (input.status !== undefined) { if (!Object.values(ExpenseStatus).includes(input.status)) { throw new Error(`Invalid status: ${input.status}`); } params.status = input.status; } // Validate payment_status if provided if (input.payment_status !== undefined) { if (!Object.values(ExpensePaymentStatus).includes(input.payment_status)) { throw new Error(`Invalid payment_status: ${input.payment_status}`); } params.payment_status = input.payment_status; } // Validate limit if provided if (input.limit !== undefined) { const limit = parseInt(input.limit.toString(), 10); if (isNaN(limit) || limit <= 0) { throw new Error("Invalid limit: must be a positive number"); } params.limit = limit; } // Validate expand if provided if (input.expand !== undefined) { if (Array.isArray(input.expand)) { params.expand = input.expand.map(String).filter((e: string) => e.trim().length > 0); } else { throw new Error("Invalid expand: must be an array of strings"); } } return params; } /** * Registers the get_expenses tool with the server * @param server The MCP server instance */ export function registerGetExpenses(_server: Server): void { registerToolHandler("get_expenses", async (request: ToolCallRequest) => { try { // Validate parameters const params = validateParams(request.params.arguments); logDebug(`Getting expenses with params: ${JSON.stringify(params)}`); // Get Brex client const brexClient = getBrexClient(); // Set default limit if not provided const limit = params.limit || 50; try { // Prepare API parameters - use user-provided expand or default to empty const apiParams: ListExpensesParams = { limit, expand: params.expand || [] // Use provided expand array or default to empty for minimal response size }; // Add filters if provided, ensuring expense_type is an array if (params.expense_type) { apiParams.expense_type = [params.expense_type]; } if (params.status) { apiParams.status = [params.status]; } if (params.payment_status) { apiParams.payment_status = [params.payment_status]; } // Call Brex API to get expenses const expenses = await brexClient.getExpenses(apiParams); // Validate expenses data if (!expenses || !Array.isArray(expenses.items)) { throw new Error("Invalid response format from Brex API"); } // Filter valid expenses const validExpenses = expenses.items.filter(isExpense); logDebug(`Found ${validExpenses.length} valid expenses`); const result = { expenses: validExpenses, meta: { total_count: validExpenses.length, requested_parameters: params } }; return { content: [{ type: "text", text: JSON.stringify(result, null, 2) }] }; } catch (apiError) { logError(`Error calling Brex API: ${apiError instanceof Error ? apiError.message : String(apiError)}`); throw new Error(`Failed to get expenses: ${apiError instanceof Error ? apiError.message : String(apiError)}`); } } catch (error) { logError(`Error in get_expenses tool: ${error instanceof Error ? error.message : String(error)}`); throw error; } }); }