MCP Etherscan Server

Instructions

Implementation Reference

• src/server.ts:266-283 (handler)

  Executes the get-contract-abi tool: validates input address using ContractSchema, fetches ABI via etherscanService, and returns it as text content.

  if (name === "get-contract-abi") {
    try {
      const { address } = ContractSchema.parse(args);
      const abi = await etherscanService.getContractABI(address);
      return {
        content: [
          { type: "text", text: `Contract ABI for ${address}:\n\n${abi}` },
        ],
      };
    } catch (error) {
      if (error instanceof z.ZodError) {
        throw new Error(
          `Invalid input: ${error.errors.map((e) => e.message).join(", ")}`
        );
      }
      throw error;
    }
  }

• src/server.ts:56-60 (schema)

  Zod schema for validating the input address parameter required by get-contract-abi tool.

  const ContractSchema = z.object({
    address: z
      .string()
      .regex(/^0x[a-fA-F0-9]{40}$/, "Invalid Ethereum address format"),
  });

• src/server.ts:123-137 (registration)

  Registers the get-contract-abi tool in the list of available tools, including its description and input schema.

  {
    name: "get-contract-abi",
    description: "Get the ABI for a smart contract",
    inputSchema: {
      type: "object",
      properties: {
        address: {
          type: "string",
          description: "Contract address (0x format)",
          pattern: "^0x[a-fA-F0-9]{40}$",
        },
      },
      required: ["address"],
    },
  },

• src/services/etherscanService.ts:131-153 (helper)

  Core implementation in EtherscanService: validates address, fetches ABI from Etherscan API using 'getabi' action, returns the ABI JSON string.

  async getContractABI(address: string): Promise<string> {
    try {
      const validAddress = ethers.getAddress(address);
      
      // Get contract ABI
      const result = await fetch(
        `https://api.etherscan.io/api?module=contract&action=getabi&address=${validAddress}&apikey=${this.provider.apiKey}`
      );
      
      const data = await result.json();
      
      if (data.status !== "1" || !data.result) {
        throw new Error(data.message || "Failed to fetch contract ABI");
      }
  
      return data.result;
    } catch (error) {
      if (error instanceof Error) {
        throw new Error(`Failed to get contract ABI: ${error.message}`);
      }
      throw error;
    }
  }