YNAB MCP Server

Instructions

Implementation Reference

• src/index.ts:57-59 (handler)

  The core handler function in YNABClient that performs the HTTP request to retrieve category details from the YNAB API.

  async getCategory(budgetId: string, categoryId: string) {
    return this.request<{ category: any }>(`/budgets/${budgetId}/categories/${categoryId}`);
  }

• src/index.ts:125-128 (schema)

  Zod schema for validating input parameters (budget_id and category_id) used for the get_category tool.

  const CategorySchema = z.object({
    budget_id: z.string().describe("The budget ID"),
    category_id: z.string().describe("The category ID"),
  });

• src/index.ts:205-216 (registration)

  Tool definition registration in the tools array provided to list_tools request handler, including name, description, and input schema.

  {
    name: "get_category",
    description: "Get detailed information about a specific category including current month data.",
    inputSchema: {
      type: "object" as const,
      properties: {
        budget_id: { type: "string", description: "The budget ID" },
        category_id: { type: "string", description: "The category ID" },
      },
      required: ["budget_id", "category_id"],
    },
  },

• src/index.ts:343-347 (registration)

  Dispatch and execution logic in the CallToolRequestSchema handler: parses args with CategorySchema and invokes the getCategory handler.

  case "get_category": {
    const { budget_id, category_id } = CategorySchema.parse(args);
    result = await client.getCategory(budget_id, category_id);
    break;
  }