LunchMoney MCP Server

Instructions

Implementation Reference

• src/tools/transactions.ts:138-179 (handler)

  Handler function that retrieves a single transaction by ID from the LunchMoney API, handles optional debit_as_negative parameter, and returns the transaction as JSON text.

      const { baseUrl, lunchmoneyApiToken } = getConfig();
  
      const params = new URLSearchParams();
      if (input.debit_as_negative !== undefined) {
          params.append(
              "debit_as_negative",
              input.debit_as_negative.toString()
          );
      }
  
      const url = params.toString()
          ? `${baseUrl}/transactions/${input.transaction_id}?${params}`
          : `${baseUrl}/transactions/${input.transaction_id}`;
  
      const response = await fetch(url, {
          headers: {
              Authorization: `Bearer ${lunchmoneyApiToken}`,
          },
      });
  
      if (!response.ok) {
          return {
              content: [
                  {
                      type: "text",
                      text: `Failed to get transaction: ${response.statusText}`,
                  },
              ],
          };
      }
  
      const transaction: Transaction = await response.json();
  
      return {
          content: [
              {
                  type: "text",
                  text: JSON.stringify(transaction),
              },
          ],
      };
  }

• src/tools/transactions.ts:126-136 (schema)

  Input schema using Zod for validating transaction_id (required number) and optional debit_as_negative (boolean). Defines the tool's input parameters.

  {
      input: z.object({
          transaction_id: z
              .number()
              .describe("ID of the transaction to retrieve"),
          debit_as_negative: z
              .boolean()
              .optional()
              .describe("Pass true to return debit amounts as negative"),
      }),
  },

• src/tools/transactions.ts:123-180 (registration)

  Registration of the 'get_single_transaction' tool on the MCP server within the registerTransactionTools function, including name, description, schema, and handler.

  server.tool(
      "get_single_transaction",
      "Get details of a specific transaction",
      {
          input: z.object({
              transaction_id: z
                  .number()
                  .describe("ID of the transaction to retrieve"),
              debit_as_negative: z
                  .boolean()
                  .optional()
                  .describe("Pass true to return debit amounts as negative"),
          }),
      },
      async ({ input }) => {
          const { baseUrl, lunchmoneyApiToken } = getConfig();
  
          const params = new URLSearchParams();
          if (input.debit_as_negative !== undefined) {
              params.append(
                  "debit_as_negative",
                  input.debit_as_negative.toString()
              );
          }
  
          const url = params.toString()
              ? `${baseUrl}/transactions/${input.transaction_id}?${params}`
              : `${baseUrl}/transactions/${input.transaction_id}`;
  
          const response = await fetch(url, {
              headers: {
                  Authorization: `Bearer ${lunchmoneyApiToken}`,
              },
          });
  
          if (!response.ok) {
              return {
                  content: [
                      {
                          type: "text",
                          text: `Failed to get transaction: ${response.statusText}`,
                      },
                  ],
              };
          }
  
          const transaction: Transaction = await response.json();
  
          return {
              content: [
                  {
                      type: "text",
                      text: JSON.stringify(transaction),
                  },
              ],
          };
      }
  );