MetaMask MCP

import type { Config } from "@wagmi/core"; import type { FastMCP } from "fastmcp"; import { sendTransaction } from "@wagmi/core"; import { Address } from "abitype/zod"; import { TransactionExecutionError } from "viem"; import { z } from "zod"; import { JSONStringify } from "../utils/json-stringify"; export function registerSendTransactionTools(server: FastMCP, wagmiConfig: Config): void { server.addTool({ name: "send-transaction", description: "Send transactions to networks.", parameters: z.object({ to: Address.describe("The transaction recipient or contract address."), data: Address.optional().describe("A contract hashed method call with encoded args."), value: z.coerce.bigint().optional().describe("Value in wei sent with this transaction."), maxFeePerGas: z.coerce.bigint().optional().describe("Total fee per gas in wei, inclusive of maxPriorityFeePerGas."), maxPriorityFeePerGas: z.coerce.bigint().optional().describe("Max priority fee per gas in wei."), chainId: z.coerce.number().optional().describe("Chain ID to validate against before sending transaction."), }), execute: async (args) => { try { const result = await sendTransaction(wagmiConfig, args); return { content: [ { type: "text", text: JSONStringify({ hash: result, }), }, ], }; } catch (error) { if (error instanceof TransactionExecutionError) { return { content: [ { type: "text", text: error.cause.message, }, ], }; } return { content: [ { type: "text", text: (error as Error).message, }, ], }; } }, }); };