getProductPrices

Instructions

Implementation Reference

• src/tools/price-tools.ts:33-63 (handler)

  The core handler function that executes the tool logic. It fetches crowd-sourced price data from the Open Food Facts Prices API for a given product barcode, with pagination support.

  async function getProductPrices(barcode: string, page: number, pageSize: number): Promise<PricesSearchResult> {
      const url = new URL(`${PRICES_URL}/prices`);
      url.searchParams.set('product_code', barcode);
      url.searchParams.set('page', page.toString());
      url.searchParams.set('size', pageSize.toString());
      url.searchParams.set('order_by', '-date');
  
      const response = await fetch(url.toString());
      if (!response.ok) {
          throw new Error(`Failed to get prices: ${response.status}`);
      }
  
      const data = await response.json();
  
      const prices = (data.items || []).map((p: any): PriceResult => ({
          productCode: p.product_code,
          price: p.price,
          currency: p.currency,
          locationName: p.location?.osm_display_name || 'Unknown location',
          locationId: p.location_id,
          date: p.date,
          proofId: p.proof_id
      }));
  
      return {
          prices,
          count: data.total || prices.length,
          page,
          pageSize
      };
  }

• src/tools/price-tools.ts:143-175 (registration)

  The registration of the 'getProductPrices' tool on the MCP server, including description, input schema, and the async handler callback that calls getProductPrices() and formats the response.

  export function registerPriceTools(server: McpServer): void {
      server.registerTool('getProductPrices', {
          description: 'Get crowd-sourced price data for a specific product - see where it costs less',
          inputSchema: productPricesSchema
      }, async ({ barcode, page, pageSize }) => {
          try {
              const result = await getProductPrices(barcode, page ?? 1, pageSize ?? 20);
  
              if (result.prices.length === 0) {
                  return {
                      content: [{
                          type: 'text' as const,
                          text: `No price data available for product ${barcode}. Price data is crowd-sourced and may not be available for all products.`
                      }]
                  };
              }
  
              let message = `Found ${result.count} price records for product ${barcode}:\n\n`;
              result.prices.forEach((p, i) => {
                  message += `${i + 1}. ${p.price} ${p.currency} at ${p.locationName}\n`;
                  message += `   Date: ${p.date}\n\n`;
              });
  
              return {
                  content: [{
                      type: 'text' as const,
                      text: message + `\n\nRaw data:\n${JSON.stringify(result, null, 2)}`
                  }]
              };
          } catch (error: any) {
              return { content: [{ type: 'text' as const, text: `Error: ${error.message}` }], isError: true };
          }
      });

• src/tools/price-tools.ts:7-11 (schema)

  The input schema for getProductPrices using Zod validation: barcode (string), page (number with default 1), pageSize (number with default 20).

  const productPricesSchema = {
      barcode: z.string().describe('Product barcode to get prices for'),
      page: z.number().default(1),
      pageSize: z.number().default(20)
  };

• src/tools/types.ts:112-128 (helper)

  Type definitions used by getProductPrices: PriceResult interface (productCode, price, currency, locationName, locationId, date, proofId) and PricesSearchResult interface (prices array, count, page, pageSize).

  // Price types
  export interface PriceResult {
      productCode: string;
      price: number;
      currency: string;
      locationName: string;
      locationId: number;
      date: string;
      proofId: number;
  }
  
  export interface PricesSearchResult {
      prices: PriceResult[];
      count: number;
      page: number;
      pageSize: number;
  }

• src/tools/types.ts:130-135 (helper)

  The PRICES_URL constant ('https://prices.openfoodfacts.org/api/v1') used by getProductPrices to construct the API endpoint.

  // Constants
  export const BASE_URL = 'https://world.openfoodfacts.org';
  export const SEARCH_API_URL = 'https://search.openfoodfacts.org';
  export const ROBOTOFF_URL = 'https://robotoff.openfoodfacts.org/api/v1';
  export const PRICES_URL = 'https://prices.openfoodfacts.org/api/v1';