mcp-swiss

Instructions

Implementation Reference

• src/modules/energy.ts:255-363 (handler)

  Implementation of the compare_electricity_tariffs tool handler in src/modules/energy.ts.

  case "compare_electricity_tariffs": {
    const municipalities = args.municipalities as string[];
    const category = (args.category as string | undefined) ?? "H4";
    const year = (args.year as string | undefined) ?? CURRENT_YEAR;
  
    if (!Array.isArray(municipalities) || municipalities.length < 2) {
      throw new Error("At least 2 municipality IDs are required for comparison.");
    }
    if (municipalities.length > 20) {
      throw new Error("Maximum 20 municipalities can be compared at once.");
    }
  
    const query = `
      query Observations($locale: String!, $priceComponent: PriceComponent!, $filters: ObservationFilters!) {
        observations(locale: $locale, filters: $filters) {
          period
          municipality
          municipalityLabel
          operator
          operatorLabel
          canton
          cantonLabel
          category
          value(priceComponent: $priceComponent)
          coverageRatio
        }
      }
    `;
  
    const data = await gql<{ observations: Observation[] }>(query, {
      locale: "de",
      priceComponent: "total",
      filters: {
        period: [year],
        municipality: municipalities,
        category: [category],
      },
    });
  
    const observations = data.observations ?? [];
  
    if (!observations.length) {
      return JSON.stringify({
        error: "No tariff data found for the given municipalities",
        municipalities,
        category,
        year,
        hint: "Use search_municipality_energy to verify BFS numbers.",
        source: "https://www.strompreis.elcom.admin.ch",
      }, null, 2);
    }
  
    // Deduplicate by municipality (keep first/cheapest operator if multiple)
    const byMunicipality = new Map<string, Observation>();
    for (const obs of observations) {
      const existing = byMunicipality.get(obs.municipality);
      if (!existing || (obs.value !== null && (existing.value === null || obs.value < existing.value))) {
        byMunicipality.set(obs.municipality, obs);
      }
    }
  
    // Sort by total price ascending
    const sorted = [...byMunicipality.values()].sort((a, b) => {
      if (a.value === null) return 1;
      if (b.value === null) return -1;
      return a.value - b.value;
    });
  
    const results = sorted.map((obs, idx) => ({
      rank: idx + 1,
      municipality: obs.municipalityLabel,
      municipalityId: obs.municipality,
      canton: obs.cantonLabel,
      operator: obs.operatorLabel,
      total_rp_per_kwh: obs.value,
      year,
      category,
    }));
  
    // Find municipalities not found in results
    const foundIds = new Set(observations.map((o) => o.municipality));
    const notFound = municipalities.filter((m) => !foundIds.has(m));
  
    const cheapest = results[0];
    const mostExpensive = results[results.length - 1];
    const spread =
      cheapest && mostExpensive && cheapest.total_rp_per_kwh !== null && mostExpensive.total_rp_per_kwh !== null
        ? +(mostExpensive.total_rp_per_kwh - cheapest.total_rp_per_kwh).toFixed(3)
        : null;
  
    return JSON.stringify(
      {
        comparison: results,
        summary: {
          cheapest: cheapest.municipality,
          most_expensive: mostExpensive.municipality,
          spread_rp_per_kwh: spread,
          category,
          categoryDescription: CATEGORY_DESCRIPTIONS[category] ?? category,
          year,
          note: "Prices in Rappen per kWh. Multiple operators per municipality: cheapest shown.",
        },
        notFound: notFound.length ? notFound : undefined,
        source: "https://www.strompreis.elcom.admin.ch",
      },
      null,
      2
    );
  }