MCP Ethers Wallet

Instructions

Implementation Reference

• src/tools/erc721.ts:457-534 (registration)

  Registration of the 'prepareERC721Transfer' MCP tool, including input schema, description, and handler function. The handler prepares unsigned transaction data by calling ethersService.prepareERC721Transfer and formats the response with NFT info and tx details.

    server.tool(
      "prepareERC721Transfer",
      "Prepare an ERC721 NFT transfer transaction for signing. Returns transaction data that can be signed and broadcast.",
      {
        contractAddress: contractAddressSchema,
        tokenId: tokenIdSchema,
        toAddress: addressSchema,
        fromAddress: addressSchema,
        provider: providerSchema,
        chainId: chainIdSchema,
        gasLimit: z.string().optional(),
        gasPrice: z.string().optional(),
        maxFeePerGas: z.string().optional(),
        maxPriorityFeePerGas: z.string().optional()
      },
      async (params) => {
        try {
          // Get NFT collection info for display
          const nftInfo = await ethersService.getERC721CollectionInfo(
            params.contractAddress,
            params.provider,
            params.chainId
          );
          
          // Prepare gas options
          const options = {
            gasLimit: params.gasLimit,
            gasPrice: params.gasPrice,
            maxFeePerGas: params.maxFeePerGas,
            maxPriorityFeePerGas: params.maxPriorityFeePerGas
          };
          
          const txRequest = await ethersService.prepareERC721Transfer(
            params.contractAddress,
            params.toAddress,
            params.tokenId,
            params.fromAddress,
            params.provider,
            params.chainId,
            options
          );
          
          return {
            content: [{ 
              type: "text", 
              text: `ERC721 Transfer Transaction Prepared:
  
  Collection: ${nftInfo.name} (${nftInfo.symbol})
  Token ID: ${params.tokenId}
  From: ${params.fromAddress}
  To: ${params.toAddress}
  
  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 NFT transfer transaction: ${error instanceof Error ? error.message : String(error)}`
            }]
          };
        }
      }
    );

• src/tools/erc721.ts:472-533 (handler)

  The core handler function that implements the tool logic: fetches collection info, prepares gas options, calls the underlying ethersService to generate unsigned tx, and returns formatted JSON transaction data.

      async (params) => {
        try {
          // Get NFT collection info for display
          const nftInfo = await ethersService.getERC721CollectionInfo(
            params.contractAddress,
            params.provider,
            params.chainId
          );
          
          // Prepare gas options
          const options = {
            gasLimit: params.gasLimit,
            gasPrice: params.gasPrice,
            maxFeePerGas: params.maxFeePerGas,
            maxPriorityFeePerGas: params.maxPriorityFeePerGas
          };
          
          const txRequest = await ethersService.prepareERC721Transfer(
            params.contractAddress,
            params.toAddress,
            params.tokenId,
            params.fromAddress,
            params.provider,
            params.chainId,
            options
          );
          
          return {
            content: [{ 
              type: "text", 
              text: `ERC721 Transfer Transaction Prepared:
  
  Collection: ${nftInfo.name} (${nftInfo.symbol})
  Token ID: ${params.tokenId}
  From: ${params.fromAddress}
  To: ${params.toAddress}
  
  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 NFT transfer transaction: ${error instanceof Error ? error.message : String(error)}`
            }]
          };
        }
      }

• src/tools/erc721.ts:460-470 (schema)

  Input schema (Zod) for the prepareERC721Transfer tool, defining parameters like contract address, token ID, addresses, chain, provider, and optional gas parameters.

  {
    contractAddress: contractAddressSchema,
    tokenId: tokenIdSchema,
    toAddress: addressSchema,
    fromAddress: addressSchema,
    provider: providerSchema,
    chainId: chainIdSchema,
    gasLimit: z.string().optional(),
    gasPrice: z.string().optional(),
    maxFeePerGas: z.string().optional(),
    maxPriorityFeePerGas: z.string().optional()