Brex MCP Server

Instructions

Implementation Reference

• src/tools/getTransactions.ts:62-110 (handler)

  Core execution logic of the get_transactions tool: parameter validation, Brex API call, transaction filtering, error handling, and JSON response formatting.

  registerToolHandler("get_transactions", async (request: ToolCallRequest) => {
    try {
      // Validate parameters
      const params = validateParams(request.params.arguments);
      logDebug(`Getting transactions for account ${params.accountId}`);
      
      // Get Brex client
      const brexClient = getBrexClient();
      
      // Set default limit if not provided
      const limit = params.limit || 50;
      
      try {
        // Call Brex API to get transactions (fallback via statements). Prefer get_cash_transactions.
        const transactions = await brexClient.getTransactions(params.accountId, undefined, limit);
        
        // Validate transactions data
        if (!transactions || !Array.isArray(transactions.items)) {
          throw new Error("Invalid response format from Brex API");
        }
        
        // Filter valid transactions
        const validTransactions = transactions.items.filter(isBrexTransaction);
        logDebug(`Found ${validTransactions.length} valid transactions out of ${transactions.items.length} total`);
        
        const result = {
          transactions: validTransactions,
          meta: {
            account_id: params.accountId,
            total_count: validTransactions.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 transactions: ${apiError instanceof Error ? apiError.message : String(apiError)}`);
      }
    } catch (error) {
      logError(`Error in get_transactions tool: ${error instanceof Error ? error.message : String(error)}`);
      throw error;
    }
  });

• src/tools/index.ts:235-251 (schema)

  Input schema definition for the get_transactions tool, exposed in the listTools MCP response.

    name: "get_transactions",
    description: "Get transactions for a Brex account",
    inputSchema: {
      type: "object",
      properties: {
        accountId: {
          type: "string",
          description: "ID of the Brex account"
        },
        limit: {
          type: "number",
          description: "Maximum number of transactions to return (default: 50)"
        }
      },
      required: ["accountId"]
    }
  },

• src/tools/getTransactions.ts:61-111 (registration)

  Registration function for the get_transactions tool that sets up the tool handler using registerToolHandler.

  export function registerGetTransactions(_server: Server): void {
    registerToolHandler("get_transactions", async (request: ToolCallRequest) => {
      try {
        // Validate parameters
        const params = validateParams(request.params.arguments);
        logDebug(`Getting transactions for account ${params.accountId}`);
        
        // Get Brex client
        const brexClient = getBrexClient();
        
        // Set default limit if not provided
        const limit = params.limit || 50;
        
        try {
          // Call Brex API to get transactions (fallback via statements). Prefer get_cash_transactions.
          const transactions = await brexClient.getTransactions(params.accountId, undefined, limit);
          
          // Validate transactions data
          if (!transactions || !Array.isArray(transactions.items)) {
            throw new Error("Invalid response format from Brex API");
          }
          
          // Filter valid transactions
          const validTransactions = transactions.items.filter(isBrexTransaction);
          logDebug(`Found ${validTransactions.length} valid transactions out of ${transactions.items.length} total`);
          
          const result = {
            transactions: validTransactions,
            meta: {
              account_id: params.accountId,
              total_count: validTransactions.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 transactions: ${apiError instanceof Error ? apiError.message : String(apiError)}`);
        }
      } catch (error) {
        logError(`Error in get_transactions tool: ${error instanceof Error ? error.message : String(error)}`);
        throw error;
      }
    });
  } 

• src/tools/index.ts:45-45 (registration)

  Invocation of registerGetTransactions during overall tool registration in registerTools.

  registerGetTransactions(server);

• src/tools/getTransactions.ts:32-55 (helper)

  Helper function to validate and parse input parameters for the get_transactions tool.

  function validateParams(input: unknown): GetTransactionsParams {
    if (!input) {
      throw new Error("Missing parameters");
    }
    const raw = input as Record<string, unknown>;
    if (!raw.accountId) {
      throw new Error("Missing required parameter: accountId");
    }
    
    const params: GetTransactionsParams = {
      accountId: String(raw.accountId)
    };
    
    // Add optional parameters if provided
    if (raw.limit !== undefined) {
      const limit = parseInt(String(raw.limit), 10);
      if (isNaN(limit) || limit <= 0) {
        throw new Error("Invalid limit: must be a positive number");
      }
      params.limit = limit;
    }
    
    return params;
  }