MCP Crypto Wallet EVM

Instructions

Implementation Reference

• src/handlers/wallet.ts:366-391 (handler)

  The core handler function that populates the transaction object using the ethers Wallet's populateTransaction method, filling in missing fields like nonce, gas, etc., based on the provider.

  export const populateTransactionHandler = async (input: any): Promise<ToolResultSchema> => {
    try {
      if (!input.transaction) {
        return createErrorResponse("Transaction is required");
      }
  
      const wallet = await getWallet(input.wallet, input.password);
  
      if (!wallet.provider) {
        return createErrorResponse("Provider is required to populate a transaction, please set the provider URL");
      }
  
      const populatedTx = await wallet.populateTransaction(input.transaction);
  
      return createSuccessResponse(
      `Transaction populated successfully
        To: ${populatedTx.to}
        From: ${populatedTx.from}
        Nonce: ${populatedTx.nonce?.toString() ?? "Not specified"}
        Gas limit: ${populatedTx.gasLimit?.toString() ?? "Not specified"}
        Gas price: ${populatedTx.gasPrice?.toString() ?? "Not specified"}
      `);
    } catch (error) {
      return createErrorResponse(`Failed to populate transaction: ${(error as Error).message}`);
    }
  };

• src/tools.ts:305-332 (schema)

  The input schema definition for the wallet_populate_transaction tool, specifying parameters like wallet and transaction object.

  {
    name: "wallet_populate_transaction",
    description: "Populate a transaction with missing fields",
    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 populate",
          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:581-581 (registration)

  The registration of the populateTransactionHandler to the 'wallet_populate_transaction' tool name in the handlers dictionary.

  "wallet_populate_transaction": populateTransactionHandler,