MCP Crypto Wallet EVM

Instructions

Implementation Reference

• src/handlers/wallet.ts:345-364 (handler)

  The main handler function that populates the transaction if needed and signs it using the Ethers.js Wallet instance.

  export const signTransactionHandler = async (input: any): Promise<ToolResultSchema> => {
    try {
      if (!input.transaction) {
        return createErrorResponse("Transaction is required");
      }
  
      const wallet = await getWallet(input.wallet, input.password);
  
      // For signing a transaction, we need to populate it first
      const populatedTx = await wallet.populateTransaction(input.transaction);
      const signedTx = await wallet.signTransaction(populatedTx);
  
      return createSuccessResponse(
      `Transaction signed successfully
        Signed transaction: ${signedTx}
      `);
    } catch (error) {
      return createErrorResponse(`Failed to sign transaction: ${(error as Error).message}`);
    }
  };

• src/tools.ts:277-304 (schema)

  Defines the tool name, description, and input schema for 'wallet_sign_transaction' in the tools array.

  {
    name: "wallet_sign_transaction",
    description: "Sign a transaction without sending it",
    inputSchema: {
      type: "object",
      properties: {
        wallet: { type: "string", description: "The wallet (private key, mnemonic, or JSON). If not provided, uses PRIVATE_KEY environment variable if set." },
        transaction: { 
          type: "object", 
          description: "The transaction to sign",
          properties: {
            to: { type: "string" },
            from: { type: "string" },
            data: { type: "string" },
            value: { type: "string" },
            gasLimit: { type: "string" },
            gasPrice: { type: "string" },
            nonce: { type: "number" },
            type: { type: "number" },
            maxFeePerGas: { type: "string" },
            maxPriorityFeePerGas: { type: "string" }
          },
          required: ["to"]
        }
      },
      required: ["transaction"]
    }
  },

• src/tools.ts:579-581 (registration)

  Registers the signTransactionHandler function to the 'wallet_sign_transaction' tool name in the handlers dictionary.

  "wallet_send_transaction": sendTransactionHandler,
  "wallet_sign_transaction": signTransactionHandler,
  "wallet_populate_transaction": populateTransactionHandler,

• src/tools.ts:16-37 (registration)

  Imports the signTransactionHandler from the handlers module.

    signTransactionHandler,
    populateTransactionHandler,
    signMessageHandler,
    signTypedDataHandler,
    verifyMessageHandler,
    verifyTypedDataHandler,
    getBlockHandler,
    getTransactionHandler,
    getTransactionReceiptHandler,
    getCodeHandler,
    getStorageAtHandler,
    estimateGasHandler,
    getLogsHandler,
    getEnsResolverHandler,
    lookupAddressHandler,
    resolveNameHandler,
    getNetworkHandler,
    getBlockNumberHandler,
    getFeeDataHandler,
    createMnemonicPhraseHandler,
    setProviderHandler
  } from "./handlers/wallet.js";