evmscope

Instructions

Implementation Reference

• src/tools/getGasPrice.ts:33-102 (handler)

  The core handler function that fetches gas estimates from the RPC client and calculates gas costs.

  async function handler(args: z.infer<typeof inputSchema>): Promise<ToolResult<GasPriceData>> {
    const { chain } = args;
  
    const cacheKey = `gas:${chain}`;
    const cached = cache.get<GasPriceData>(cacheKey);
    if (cached.hit) return makeSuccess(chain, cached.data, true);
  
    try {
      const client = getClient(chain);
  
      const [block, maxPriorityFee] = await Promise.all([
        client.getBlock({ blockTag: "latest" }),
        client.estimateMaxPriorityFeePerGas(),
      ]);
  
      const baseFee = block.baseFeePerGas ?? 0n;
  
      const prioritySlow = maxPriorityFee * 80n / 100n;
      const priorityNormal = maxPriorityFee;
      const priorityFast = maxPriorityFee * 150n / 100n;
  
      const maxFeeSlow = baseFee + prioritySlow;
      const maxFeeNormal = baseFee + priorityNormal;
      const maxFeeFast = baseFee + priorityFast;
  
      let ethPriceUsd = 0;
      try {
        const nativeCoingeckoId = getNativeCoingeckoId(chain);
        if (nativeCoingeckoId) {
          const priceData = await getPrice(nativeCoingeckoId);
          ethPriceUsd = priceData.priceUsd;
        }
      } catch {
        // 가격 조회 실패해도 가스비 자체는 반환
      }
  
      function calcCostUsd(maxFeeGwei: bigint): number {
        if (ethPriceUsd === 0) return 0;
        const costWei = maxFeeGwei * STANDARD_GAS;
        const costEth = Number(costWei) / 1e18;
        return Math.round(costEth * ethPriceUsd * 10000) / 10000;
      }
  
      const data: GasPriceData = {
        slow: {
          maxFeePerGas: formatGwei(maxFeeSlow),
          maxPriorityFeePerGas: formatGwei(prioritySlow),
          estimatedCostUsd: calcCostUsd(maxFeeSlow),
        },
        normal: {
          maxFeePerGas: formatGwei(maxFeeNormal),
          maxPriorityFeePerGas: formatGwei(priorityNormal),
          estimatedCostUsd: calcCostUsd(maxFeeNormal),
        },
        fast: {
          maxFeePerGas: formatGwei(maxFeeFast),
          maxPriorityFeePerGas: formatGwei(priorityFast),
          estimatedCostUsd: calcCostUsd(maxFeeFast),
        },
        baseFee: formatGwei(baseFee),
        lastBlock: Number(block.number),
      };
  
      cache.set(cacheKey, data, GAS_CACHE_TTL);
      return makeSuccess(chain, data, false);
    } catch (err) {
      const message = sanitizeError(err);
      return makeError(`Failed to fetch gas price: ${message}`, "RPC_ERROR");
    }
  }

• src/tools/getGasPrice.ts:29-31 (schema)

  Input validation schema for the getGasPrice tool.

  const inputSchema = z.object({
    chain: z.enum(SUPPORTED_CHAINS).default("ethereum").describe("EVM 체인"),
  });

• src/tools/getGasPrice.ts:104-114 (registration)

  Tool registration for getGasPrice in the MCP server.

  export function register(server: McpServer) {
    server.tool(
      "getGasPrice",
      "현재 가스비를 slow/normal/fast 3단계로 조회합니다 (Gwei + USD 예상 비용)",
      inputSchema.shape,
      async (args) => {
        const result = await handler(args as z.infer<typeof inputSchema>);
        return { content: [{ type: "text" as const, text: JSON.stringify(result, null, 2) }] };
      },
    );
  }