MetaMask MCP

import type { Config } from "@wagmi/core"; import type { FastMCP } from "fastmcp"; import { switchChain } from "@wagmi/core"; import { z } from "zod"; import { JSONStringify } from "../utils/json-stringify"; export function registerSwitchChainTools(server: FastMCP, wagmiConfig: Config): void { server.addTool({ name: "switch-chain", description: "Switch the target chain.", parameters: z.object({ chainId: z.coerce.number().describe("ID of chain to switch to."), addEthereumChainParameter: z.object({ chainName: z.string(), nativeCurrency: z.object({ name: z.string(), symbol: z.string(), decimals: z.coerce.number(), }), rpcUrls: z.string().array().min(1), blockExplorerUrls: z.string().array().optional(), iconUrls: z.string().array().optional(), }).optional().describe("Add not configured chains to Ethereum wallets."), }), execute: async (args) => { const chainId = args.chainId as typeof wagmiConfig["chains"][number]["id"]; const addEthereumChainParameter = args.addEthereumChainParameter; const result = await switchChain(wagmiConfig, { chainId, addEthereumChainParameter, }); wagmiConfig._internal.chains.setState(x => [...x, result]); return { content: [ { type: "text", text: JSONStringify(result), }, ], }; }, }); };