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JagjeevanAK

OpenFoodFacts-mcp

by JagjeevanAK

searchByCategory

Find food products by category (e.g., beverages, snacks, dairy) from OpenFoodFacts database. Specify category to retrieve product listings.

Instructions

Search products within a specific food category (e.g., beverages, snacks, dairy, cereals)

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
categoryYesFood category (e.g., "beverages", "snacks", "dairy", "organic")
pageNo
pageSizeNo

Implementation Reference

  • The actual implementation of searchByCategory. It takes a category string (e.g., 'beverages'), converts it to a slug, calls the Open Food Facts category API, maps results using mapToSearchProduct, and returns a SearchResult with pagination info.
    export async function searchByCategory(category: string, page: number, pageSize: number): Promise<SearchResult> {
        const categorySlug = category.toLowerCase().replace(/\s+/g, '-');
        const url = `${BASE_URL}/category/${categorySlug}/${page}.json`;
    
        const response = await fetch(url);
        if (!response.ok) {
            throw new Error(`Failed to search by category: ${response.status}`);
        }
    
        const data = await response.json();
    
        return {
            products: (data.products || []).map(mapToSearchProduct),
            count: data.count || 0,
            page,
            pageSize,
            pageCount: Math.ceil((data.count || 0) / pageSize)
        };
    }
  • Registration of the 'searchByCategory' tool on the MCP server via server.registerTool(). Defines the description and uses categorySchema for input validation. The handler calls the searchByCategory helper and returns the JSON-stringified result.
    server.registerTool('searchByCategory', {
        description: 'Search products within a specific food category (e.g., beverages, snacks, dairy, cereals)',
        inputSchema: categorySchema
    }, async ({ category, page, pageSize }) => {
        try {
            const results = await searchByCategory(category, page ?? 1, pageSize ?? 10);
            return { content: [{ type: 'text' as const, text: JSON.stringify(results, null, 2) }] };
        } catch (error: any) {
            return { content: [{ type: 'text' as const, text: `Error: ${error.message}` }], isError: true };
        }
    });
  • Input schema for searchByCategory defined with Zod: category (string), page (number, default 1), pageSize (number, default 10).
    const categorySchema = {
        category: z.string().describe('Food category (e.g., "beverages", "snacks", "dairy", "organic")'),
        page: z.number().default(1),
        pageSize: z.number().default(10)
    };
  • Helper function mapToSearchProduct used by searchByCategory to map raw product data from the API into the SearchProductResult format.
    export function mapToSearchProduct(p: any): SearchProductResult {
        return {
            id: p._id || p.code,
            name: p.product_name || 'Unknown',
            brand: p.brands || 'Unknown',
            barcode: p.code || '',
            imageUrl: p.image_url || '',
            nutriScore: p.nutriscore_grade || '',
            ecoScore: p.ecoscore_grade || '',
            novaGroup: p.nova_group || 0,
            categories: p.categories || ''
        };
    }
  • Log line confirming registration of the searchByCategory tool (and others).
    logger.info("Category tools registered: searchByCategory, searchByBrand, advancedSearch, autocomplete");

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.1.0

TDQS

C2.7/5.0
Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description fails to disclose pagination behavior, result limits, or matching criteria beyond the category name.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Short and to the point, but overly minimalistic; could be structured with bullet points or additional details without being verbose.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Adequate for a simple search tool, but lacks information on response format, pagination details, or how categories are matched, especially given no output schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Only repeats the category parameter examples from the schema; does not explain page or pageSize parameters despite low schema coverage (33%).

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool searches products by food category with examples, but it does not differentiate from sibling tools like searchByBrand or searchProducts.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance on when to use this tool versus alternatives; lacks any 'when to use' or 'when not to use' context.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.