Open MCP Server

Implementation Reference

• src/tools/file-tools.ts:62-83 (handler)

  The handler function for the 'write_file' tool. It validates the file path, optionally creates parent directories, writes the provided content to the file using fs.writeFile, and returns a success message with the character count.

  async ({ path: filePath, content, encoding, createDirectories }) => {
    return wrapToolExecution(async () => {
      const validatedPath = await validatePath(filePath);
  
      if (createDirectories) {
        const dir = path.dirname(validatedPath);
        await fs.mkdir(dir, { recursive: true });
      }
  
      await fs.writeFile(validatedPath, content, { encoding: encoding as FileEncoding });
  
      return {
        content: [{
          type: "text" as const,
          text: `Successfully wrote ${content.length} characters to ${validatedPath}`
        }]
      };
    }, {
      errorCode: ERROR_CODES.FILE_OPERATION,
      context: "Failed to write file"
    });
  }

• src/tools/file-tools.ts:56-61 (schema)

  Zod schema defining the input parameters for the 'write_file' tool: path (required string), content (string), encoding (optional enum), createDirectories (optional boolean).

  {
    path: z.string().min(1, "Path is required"),
    content: z.string(),
    encoding: z.enum(["utf8", "utf-16le", "latin1"]).optional().default(DEFAULTS.FILE_ENCODING),
    createDirectories: z.boolean().optional().default(DEFAULTS.CREATE_DIRECTORIES)
  },

• src/tools/file-tools.ts:54-85 (registration)

  The registerWriteFile function that registers the 'write_file' tool on the MCP server using server.tool(), including the schema and handler.

  function registerWriteFile(server: McpServer): void {
    server.tool("write_file",
      {
        path: z.string().min(1, "Path is required"),
        content: z.string(),
        encoding: z.enum(["utf8", "utf-16le", "latin1"]).optional().default(DEFAULTS.FILE_ENCODING),
        createDirectories: z.boolean().optional().default(DEFAULTS.CREATE_DIRECTORIES)
      },
      async ({ path: filePath, content, encoding, createDirectories }) => {
        return wrapToolExecution(async () => {
          const validatedPath = await validatePath(filePath);
  
          if (createDirectories) {
            const dir = path.dirname(validatedPath);
            await fs.mkdir(dir, { recursive: true });
          }
  
          await fs.writeFile(validatedPath, content, { encoding: encoding as FileEncoding });
  
          return {
            content: [{
              type: "text" as const,
              text: `Successfully wrote ${content.length} characters to ${validatedPath}`
            }]
          };
        }, {
          errorCode: ERROR_CODES.FILE_OPERATION,
          context: "Failed to write file"
        });
      }
    );
  }

• src/index.ts:65-65 (registration)

  Top-level registration call in the main server initialization that invokes registerFileTools, which includes the write_file tool.

  registerFileTools(server);