base-flash-arb-mcp

Instructions

Implementation Reference

• src/index.ts:1043-1107 (handler)

  The implementation of the get_price_across_dexes MCP tool, which fetches token prices across multiple DEXes on Base and calculates the spread.

  server.tool(
    "get_price_across_dexes",
    "Get current price of a token on all available DEXes on Base.",
    {
      token_address: z.string().describe("Token contract address on Base"),
    },
    async ({ token_address }) => {
      try {
        const [symbol, decimals] = await Promise.all([
          getSymbol(token_address),
          getDecimals(token_address),
        ]);
  
        const testAmount = ethers.parseEther("0.001"); // Small test amount
        const buyQuotes = await getAllBuyQuotes(token_address, testAmount);
  
        const prices = buyQuotes.map((q) => {
          // Price = ETH spent / tokens received
          const tokensOut = Number(
            ethers.formatUnits(q.amountOut, decimals)
          );
          const ethIn = Number(ethers.formatEther(testAmount));
          const priceInEth = tokensOut > 0 ? ethIn / tokensOut : 0;
          const tokensPerEth = tokensOut > 0 ? tokensOut : 0;
  
          return {
            dex: q.label,
            tokensPerEth: tokensPerEth.toFixed(4),
            pricePerTokenEth: priceInEth.toFixed(18),
            pricePerTokenUsd: (priceInEth * 2500).toFixed(6), // approximate
          };
        });
  
        // Calculate spread
        const priceValues = prices.map((p) => parseFloat(p.pricePerTokenEth));
        const minPrice = Math.min(...priceValues);
        const maxPrice = Math.max(...priceValues);
        const spreadBps =
          minPrice > 0
            ? Math.round(((maxPrice - minPrice) / minPrice) * 10000)
            : 0;
  
        return {
          content: [
            {
              type: "text" as const,
              text: JSON.stringify(
                {
                  token: token_address,
                  symbol,
                  decimals,
                  testAmountEth: "0.001",
                  dexCount: prices.length,
                  spreadBps,
                  prices,
                },
                null,
                2
              ),
            },
          ],
        };
      } catch (e) {
        return {
          content: [