Foundry MCP Server

import { z } from "zod"; import { exec } from "child_process"; import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js"; import { checkFoundryInstalled, FOUNDRY_PATHS, FOUNDRY_NOT_INSTALLED_ERROR } from "../../utils/command.js"; import { getAnvilInfo } from "../../utils/rpc.js"; export function registerAnvilStartTool(server: McpServer): void { server.tool( "anvil_start", "Start a new Anvil instance (local Ethereum node)", { port: z.number().optional().describe("Port to listen on (default: 8545)"), blockTime: z.number().optional().describe("Block time in seconds (default: 0 - mine on demand)"), forkUrl: z.string().optional().describe("URL of the JSON-RPC endpoint to fork from"), forkBlockNumber: z.number().optional().describe("Block number to fork from"), accounts: z.number().optional().describe("Number of accounts to generate (default: 10)"), mnemonic: z.string().optional().describe("BIP39 mnemonic phrase to generate accounts from"), silent: z.boolean().optional().describe("Suppress anvil output (default: false)") }, async ({ port = 8545, blockTime, forkUrl, forkBlockNumber, accounts, mnemonic, silent = false }) => { const installed = await checkFoundryInstalled(); if (!installed) { return { content: [{ type: "text", text: FOUNDRY_NOT_INSTALLED_ERROR }], isError: true }; } // Check if anvil is already running const anvilInfo = await getAnvilInfo(); if (anvilInfo.running) { return { content: [{ type: "text", text: `Anvil is already running on port ${anvilInfo.port}.` }], isError: true }; } let command = `${FOUNDRY_PATHS.anvilPath} --port ${port}`; if (blockTime !== undefined) { command += ` --block-time ${blockTime}`; } if (forkUrl) { command += ` --fork-url "${forkUrl}"`; if (forkBlockNumber !== undefined) { command += ` --fork-block-number ${forkBlockNumber}`; } } if (accounts !== undefined) { command += ` --accounts ${accounts}`; } if (mnemonic) { command += ` --mnemonic "${mnemonic}"`; } try { // Start anvil in the background const child = exec(command, (error, stdout, stderr) => { if (error && !silent) { console.error(`Anvil error: ${error.message}`); } if (stderr && !silent) { console.error(`Anvil stderr: ${stderr}`); } if (stdout && !silent) { console.log(`Anvil stdout: ${stdout}`); } }); // Give it a moment to start await new Promise(resolve => setTimeout(resolve, 1000)); // Check if it started successfully const newAnvilInfo = await getAnvilInfo(); if (newAnvilInfo.running) { return { content: [{ type: "text", text: `Anvil started successfully on port ${port}. ` + `RPC URL: http://localhost:${port}\n` + `Process ID: ${child.pid}` }] }; } else { return { content: [{ type: "text", text: `Failed to start Anvil. Check system logs for details.` }], isError: true }; } } catch (error) { return { content: [{ type: "text", text: `Error starting Anvil: ${error instanceof Error ? error.message : String(error)}` }], isError: true }; } } ); }