MCP Ethers Wallet

Instructions

Implementation Reference

• src/tools/erc20.ts:323-413 (registration)

  Registration of the 'prepareERC20Transfer' MCP tool including input schema definition and complete handler implementation. The handler prepares an unsigned ERC20 transfer transaction.

    server.tool(
      "prepareERC20Transfer",
      "Prepare an ERC20 token transfer transaction for signing. Returns transaction data that can be signed and broadcast.",
      {
        contractAddress: contractAddressSchema,
        tokenAddress: tokenAddressSchema.optional(),  // Deprecated
        recipientAddress: z.string().describe(
          "The Ethereum address to receive the tokens"
        ),
        amount: amountSchema,
        fromAddress: z.string().describe(
          "The Ethereum address sending the tokens"
        ),
        provider: providerSchema,
        chainId: chainIdSchema,
        gasLimit: z.string().optional(),
        gasPrice: z.string().optional(),
        maxFeePerGas: z.string().optional(),
        maxPriorityFeePerGas: z.string().optional()
      },
      async (params) => {
        // Map deprecated parameters
        const mapped = mapParameters(params);
        
        try {
          const contractAddr = mapped.contractAddress || params.tokenAddress;
          if (!contractAddr) {
            throw new Error('Either contractAddress or tokenAddress must be provided');
          }
  
          // Get token info for display
          const tokenInfo = await ethersService.getERC20TokenInfo(
            contractAddr,
            mapped.provider,
            mapped.chainId
          );
          
          // Prepare gas options
          const options = {
            gasLimit: params.gasLimit,
            gasPrice: params.gasPrice,
            maxFeePerGas: params.maxFeePerGas,
            maxPriorityFeePerGas: params.maxPriorityFeePerGas
          };
          
          const txRequest = await ethersService.prepareERC20Transfer(
            contractAddr,
            mapped.recipientAddress,
            mapped.amount,
            mapped.fromAddress,
            mapped.provider,
            mapped.chainId,
            options
          );
          
          return {
            content: [{ 
              type: "text", 
              text: `ERC20 Transfer Transaction Prepared:
  
  Token: ${tokenInfo.name} (${tokenInfo.symbol})
  From: ${mapped.fromAddress}
  To: ${mapped.recipientAddress}
  Amount: ${mapped.amount} ${tokenInfo.symbol}
  
  Transaction Data:
  ${JSON.stringify({
    to: txRequest.to,
    data: txRequest.data,
    value: txRequest.value || "0",
    gasLimit: txRequest.gasLimit?.toString(),
    gasPrice: txRequest.gasPrice?.toString(),
    maxFeePerGas: txRequest.maxFeePerGas?.toString(),
    maxPriorityFeePerGas: txRequest.maxPriorityFeePerGas?.toString(),
    chainId: txRequest.chainId
  }, null, 2)}
  
  This transaction is ready to be signed and broadcast.`
            }]
          };
        } catch (error) {
          return {
            isError: true,
            content: [{ 
              type: "text", 
              text: `Error preparing transfer transaction: ${error instanceof Error ? error.message : String(error)}`
            }]
          };
        }
      }
    );

• src/tools/erc20.ts:343-412 (handler)

  Core handler logic for executing the prepareERC20Transfer tool: parameter mapping, validation, token info retrieval, transaction preparation via ethersService, and response formatting.

      async (params) => {
        // Map deprecated parameters
        const mapped = mapParameters(params);
        
        try {
          const contractAddr = mapped.contractAddress || params.tokenAddress;
          if (!contractAddr) {
            throw new Error('Either contractAddress or tokenAddress must be provided');
          }
  
          // Get token info for display
          const tokenInfo = await ethersService.getERC20TokenInfo(
            contractAddr,
            mapped.provider,
            mapped.chainId
          );
          
          // Prepare gas options
          const options = {
            gasLimit: params.gasLimit,
            gasPrice: params.gasPrice,
            maxFeePerGas: params.maxFeePerGas,
            maxPriorityFeePerGas: params.maxPriorityFeePerGas
          };
          
          const txRequest = await ethersService.prepareERC20Transfer(
            contractAddr,
            mapped.recipientAddress,
            mapped.amount,
            mapped.fromAddress,
            mapped.provider,
            mapped.chainId,
            options
          );
          
          return {
            content: [{ 
              type: "text", 
              text: `ERC20 Transfer Transaction Prepared:
  
  Token: ${tokenInfo.name} (${tokenInfo.symbol})
  From: ${mapped.fromAddress}
  To: ${mapped.recipientAddress}
  Amount: ${mapped.amount} ${tokenInfo.symbol}
  
  Transaction Data:
  ${JSON.stringify({
    to: txRequest.to,
    data: txRequest.data,
    value: txRequest.value || "0",
    gasLimit: txRequest.gasLimit?.toString(),
    gasPrice: txRequest.gasPrice?.toString(),
    maxFeePerGas: txRequest.maxFeePerGas?.toString(),
    maxPriorityFeePerGas: txRequest.maxPriorityFeePerGas?.toString(),
    chainId: txRequest.chainId
  }, null, 2)}
  
  This transaction is ready to be signed and broadcast.`
            }]
          };
        } catch (error) {
          return {
            isError: true,
            content: [{ 
              type: "text", 
              text: `Error preparing transfer transaction: ${error instanceof Error ? error.message : String(error)}`
            }]
          };
        }
      }

• src/tools/erc20.ts:326-342 (schema)

  Input schema definition for the prepareERC20Transfer tool using Zod schemas for validation including contract address, recipient, amount, from address, provider options, and gas parameters.

  {
    contractAddress: contractAddressSchema,
    tokenAddress: tokenAddressSchema.optional(),  // Deprecated
    recipientAddress: z.string().describe(
      "The Ethereum address to receive the tokens"
    ),
    amount: amountSchema,
    fromAddress: z.string().describe(
      "The Ethereum address sending the tokens"
    ),
    provider: providerSchema,
    chainId: chainIdSchema,
    gasLimit: z.string().optional(),
    gasPrice: z.string().optional(),
    maxFeePerGas: z.string().optional(),
    maxPriorityFeePerGas: z.string().optional()
  },

• src/tools/index.ts:24-24 (registration)

  Top-level registration call for all ERC20 tools including prepareERC20Transfer via registerERC20Tools.

  registerERC20Tools(server, ethersService);