File Operation MCP Server

import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'; import { z } from 'zod'; import fs from 'fs-extra'; import * as path from 'path'; /** * Tool: Write to a file * Registers the tool with the MCP server * @param server MCP server instance */ const registerTool = (server: McpServer) => { server.registerTool( 'write-file', { title: 'Write to File', description: "Writes content to a specified file, with options for encoding, mode, and atomic operations. Accepts string or Buffer for content.", inputSchema: { filePath: z.string().describe("The path of the file to write to."), content: z.union([z.string(), z.instanceof(Buffer)]).describe("The content to write, can be a string or a Buffer for binary data."), encoding: z.string().optional().default('utf-8').describe("Specifies the file's character encoding. Only used for text modes ('w', 'a')."), mode: z.enum(['w', 'a', 'wb', 'ab']).optional().default('w').describe("File opening mode: 'w' (write, overwrites), 'a' (append to end), 'wb' (write bytes), 'ab' (append bytes)."), atomic: z.boolean().optional().default(false).describe("If true, performs an atomic write by using a temporary file. This ensures data integrity."), } }, async ({ filePath, content, encoding, mode, atomic }) => { try { const dir = path.dirname(filePath); await fs.ensureDir(dir); const isBinaryMode = mode.endsWith('b'); if (isBinaryMode && typeof content === 'string') { return { content: [{ type: 'text', text: "Error: In binary mode ('wb' or 'ab'), content must be a Buffer." }], isError: true }; } if (!isBinaryMode && content instanceof Buffer) { return { content: [{ type: 'text', text: "Error: To write a Buffer, use a binary mode ('wb' or 'ab')." }], isError: true }; } const options = { encoding: isBinaryMode ? undefined : (encoding as BufferEncoding), flag: mode }; if (atomic) { const tempFile = filePath + `.${Date.now()}.tmp`; await fs.writeFile(tempFile, content, options); await fs.rename(tempFile, filePath); } else { await fs.writeFile(filePath, content, options); } return { content: [ { type: 'text', text: `Successfully wrote ${content instanceof Buffer ? `${content.length} bytes` : 'content'} to ${filePath}` } ] }; } catch (error) { const errorMessage = error instanceof Error ? error.message : String(error); return { content: [{ type: 'text', text: `An unexpected error occurred while writing to file: ${errorMessage}` }], isError: true }; } } ); }; export default registerTool;