Etherscan MCP Tool

Instructions

Implementation Reference

• index.ts:283-305 (handler)

  The main handler function for the get_chain_id tool. It extracts the chain_name from the request, looks it up in the chainIdMapping, and returns a text response with the chain ID or an error if not found.

  async function handleGetChainId(req: any) {
      const chainName = req.params.arguments.chain_name;
  
      if (chainIdMapping[chainName] != null) {
          return {
              content: [
                  {
                      type: "text",
                      text: `Chain ID for ${chainName}: ${chainIdMapping[chainName]}`,
                  },
              ]
          };
      } else {
          return {
              content: [
                  {
                      type: "text",
                      text: `Chain ${chainName} not found`
                  }
              ]
          };
      }
  }

• index.ts:97-110 (schema)

  ToolDefinition object defining the name, description, and input schema for the get_chain_id tool.

  const getChainId: ToolDefinition = {
      name: "get_chain_id",
      description: "Get the chain ID for a given chain name",
      inputSchema: {
          type: "object",
          properties: {
              chain_name: {
                  type: "string",
                  description: "The name of the chain to get the chain ID for"
              }
          },
          required: ["chain_name"]
      }
  };

• index.ts:34-95 (helper)

  Static mapping of chain names to their corresponding chain IDs, used by the get_chain_id handler to resolve chain_names to numeric IDs.

  const chainIdMapping: { [key: string]: number } = {
      "Ethereum Mainnet": 1,
      "Sepolia Testnet": 11155111,
      "Holesky Testnet": 17000,
      "Abstract Mainnet": 2741,
      "Abstract Sepolia Testnet": 11124,
      "ApeChain Curtis Testnet": 33111,
      "ApeChain Mainnet": 33139,
      "Arbitrum Nova Mainnet": 42170,
      "Arbitrum One Mainnet": 42161,
      "Arbitrum Sepolia Testnet": 421614,
      "Avalanche C-Chain": 43114,
      "Avalanche Fuji Testnet": 43113,
      "Base Mainnet": 8453,
      "Base Sepolia Testnet": 84532,
      "Berachain Mainnet": 80094,
      "BitTorrent Chain Mainnet": 199,
      "BitTorrent Chain Testnet": 1028,
      "Blast Mainnet": 81457,
      "Blast Sepolia Testnet": 168587773,
      "BNB Smart Chain Mainnet": 56,
      "BNB Smart Chain Testnet": 97,
      "Celo Alfajores Testnet": 44787,
      "Celo Mainnet": 42220,
      "Cronos Mainnet": 25,
      "Fraxtal Mainnet": 252,
      "Fraxtal Testnet": 2522,
      "Gnosis": 100,
      "Linea Mainnet": 59144,
      "Linea Sepolia Testnet": 59141,
      "Mantle Mainnet": 5000,
      "Mantle Sepolia Testnet": 5003,
      "Moonbase Alpha Testnet": 1287,
      "Moonbeam Mainnet": 1284,
      "Moonriver Mainnet": 1285,
      "OP Mainnet": 10,
      "OP Sepolia Testnet": 11155420,
      "Polygon Amoy Testnet": 80002,
      "Polygon Mainnet": 137,
      "Polygon zkEVM Cardona Testnet": 2442,
      "Polygon zkEVM Mainnet": 1101,
      "Scroll Mainnet": 534352,
      "Scroll Sepolia Testnet": 534351,
      "Sonic Blaze Testnet": 57054,
      "Sonic Mainnet": 146,
      "Sophon Mainnet": 50104,
      "Sophon Sepolia Testnet": 531050104,
      "Taiko Hekla L2 Testnet": 167009,
      "Taiko Mainnet": 167000,
      "Unichain Mainnet": 130,
      "Unichain Sepolia Testnet": 1301,
      "WEMIX3.0 Mainnet": 1111,
      "WEMIX3.0 Testnet": 1112,
      "World Mainnet": 480,
      "World Sepolia Testnet": 4801,
      "Xai Mainnet": 660279,
      "Xai Sepolia Testnet": 37714555429,
      "XDC Apothem Testnet": 51,
      "XDC Mainnet": 50,
      "zkSync Mainnet": 324,
      "zkSync Sepolia Testnet": 300,
  };

• index.ts:216-223 (registration)

  toolDefinitions object where getChainId is registered by name, used for MCP capabilities and listTools.

  const toolDefinitions: { [key: string]: ToolDefinition } = {
      [getFilteredRpcList.name]: getFilteredRpcList,
      [getChainId.name]: getChainId,
      [getTotalSupply.name]: getTotalSupply,
      [getTokenBalance.name]: getTokenBalance,
      [getTokenHolders.name]: getTokenHolders,
      [getTokenHoldersCount.name]: getTokenHoldersCount
  };

• index.ts:481-482 (registration)

  Switch case in callToolHandler that routes calls to get_chain_id to the handleGetChainId function.

  case getChainId.name:
      return await handleGetChainId(req);