Foundry MCP Server

import { z } from "zod"; import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js"; import { checkFoundryInstalled, executeCommand, FOUNDRY_PATHS, FOUNDRY_NOT_INSTALLED_ERROR } from "../../utils/command.js"; import { resolveRpcUrl } from "../../utils/rpc.js"; export function registerCastCallTool(server: McpServer): void { server.tool( "cast_call", "Call a contract function (read-only)", { contractAddress: z.string().describe("Address of the contract"), functionSignature: z.string().describe("Function signature (e.g., 'balanceOf(address)')"), args: z.array(z.string()).optional().describe("Function arguments"), rpcUrl: z.string().optional().describe("JSON-RPC URL (default: http://localhost:8545)"), blockNumber: z.string().optional().describe("Block number (e.g., 'latest', 'earliest', or a number)"), from: z.string().optional().describe("Address to perform the call as") }, async ({ contractAddress, functionSignature, args = [], rpcUrl, blockNumber, from }) => { const installed = await checkFoundryInstalled(); if (!installed) { return { content: [{ type: "text", text: FOUNDRY_NOT_INSTALLED_ERROR }], isError: true }; } const resolvedRpcUrl = await resolveRpcUrl(rpcUrl); let command = `${FOUNDRY_PATHS.castPath} call ${contractAddress} "${functionSignature}"`; if (args.length > 0) { command += " " + args.join(" "); } if (resolvedRpcUrl) { command += ` --rpc-url "${resolvedRpcUrl}"`; } if (blockNumber) { command += ` --block ${blockNumber}`; } if (from) { command += ` --from ${from}`; } const result = await executeCommand(command); let formattedOutput = result.message; if (result.success) { // Try to detect arrays and format them better if (formattedOutput.includes('\n') && !formattedOutput.includes('Error')) { formattedOutput = formattedOutput.split('\n') .map(line => line.trim()) .filter(line => line.length > 0) .join('\n'); } } return { content: [{ type: "text", text: result.success ? `Call to ${contractAddress}.${functionSignature.split('(')[0]} result:\n${formattedOutput}` : `Call failed: ${result.message}` }], isError: !result.success }; } ); }