Arbitrum MCP Server

Instructions

Implementation Reference

• src/index.ts:306-322 (handler)

  Handler for the 'is_contract' MCP tool. Resolves RPC URL, creates EthereumAccountClient instance, calls isContract(address), and returns whether the address is a contract.

  case "is_contract": {
    const rpcUrl = await this.resolveRpcUrl(
      (args.rpcUrl as string) || (args.chainName as string)
    );
    const ethereumAccountClient = new EthereumAccountClient(rpcUrl);
    const isContract = await ethereumAccountClient.isContract(
      args.address as string
    );
    return {
      content: [
        {
          type: "text",
          text: `Is contract: ${isContract}`,
        },
      ],
    };
  }

• src/index.ts:1020-1037 (schema)

  Input schema definition for the 'is_contract' tool, specifying parameters rpcUrl (optional) and address (required). Part of the tools list returned by list tools request.

    name: "is_contract",
    description: "Check if an address is a contract",
    inputSchema: {
      type: "object" as const,
      properties: {
        rpcUrl: {
          type: "string",
          description:
            "The RPC URL of the chain (optional if default is set)",
        },
        address: {
          type: "string",
          description: "Address to check",
        },
      },
      required: ["address"],
    },
  },

• src/index.ts:1020-1037 (registration)

  Tool registration in the getAvailableTools() method, which defines the 'is_contract' tool name, description, and schema for the MCP list tools endpoint.

    name: "is_contract",
    description: "Check if an address is a contract",
    inputSchema: {
      type: "object" as const,
      properties: {
        rpcUrl: {
          type: "string",
          description:
            "The RPC URL of the chain (optional if default is set)",
        },
        address: {
          type: "string",
          description: "Address to check",
        },
      },
      required: ["address"],
    },
  },

• src/clients/ethereum-account-client.ts:106-109 (helper)

  Core helper function in EthereumAccountClient that implements the contract check logic by fetching bytecode via getCode and checking if it's non-empty ('0x'). Called by the tool handler.

  async isContract(address: string): Promise<boolean> {
    const code = await this.getCode(address);
    return code !== '0x';
  }