YNAB MCP Server

Instructions

Implementation Reference

• src/index.ts:385-389 (handler)

  MCP tool handler for 'get_month': parses arguments using MonthSchema and invokes the YNABClient.getMonth method.

  case "get_month": {
    const { budget_id, month } = MonthSchema.parse(args);
    result = await client.getMonth(budget_id, month);
    break;
  }

• src/index.ts:110-112 (helper)

  YNABClient method implementing the core logic: fetches the specific month's budget data from the YNAB API.

  async getMonth(budgetId: string, month: string) {
    return this.request<{ month: any }>(`/budgets/${budgetId}/months/${month}`);
  }

• src/index.ts:144-147 (schema)

  Zod schema used to validate and parse input arguments for the get_month tool.

  const MonthSchema = z.object({
    budget_id: z.string().describe("The budget ID"),
    month: z.string().describe("The budget month in ISO format (YYYY-MM-01)"),
  });

• src/index.ts:278-289 (registration)

  Registers the 'get_month' tool in the MCP tools list, including name, description, and JSON input schema.

  {
    name: "get_month",
    description: "Get detailed budget information for a specific month including all category balances.",
    inputSchema: {
      type: "object" as const,
      properties: {
        budget_id: { type: "string", description: "The budget ID" },
        month: { type: "string", description: "The budget month (YYYY-MM-01)" },
      },
      required: ["budget_id", "month"],
    },
  },