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'; }