Desktop Commander MCP

Instructions

Implementation Reference

• src/tools/filesystem.ts:70-73 (handler)

  Core handler function that validates the file path security and writes the provided content to the file using Node.js fs.promises.writeFile.

  export async function writeFile(filePath: string, content: string): Promise<void> {
      const validPath = await validatePath(filePath);
      await fs.writeFile(validPath, content, "utf-8");
  }

• src/tools/schemas.ts:40-43 (schema)

  Zod schema for validating the input arguments to the write_file tool: path (string) and content (string). Used in tool registration and dispatch.

  export const WriteFileArgsSchema = z.object({
    path: z.string(),
    content: z.string(),
  });

• src/server.ts:142-148 (registration)

  Tool metadata registration in the ListTools response, including name, description, and input schema reference.

  {
    name: "write_file",
    description:
      "Completely replace file contents. Best for large changes (>20% of file) or when edit_block fails. " +
      "Use with caution as it will overwrite existing files. Only works within allowed directories.",
    inputSchema: zodToJsonSchema(WriteFileArgsSchema),
  },

• src/server.ts:280-286 (handler)

  Dispatch handler in the CallToolRequest that parses arguments with the schema and delegates to the core writeFile function.

  case "write_file": {
    const parsed = WriteFileArgsSchema.parse(args);
    await writeFile(parsed.path, parsed.content);
    return {
      content: [{ type: "text", text: `Successfully wrote to ${parsed.path}` }],
    };
  }