diff --git a/pkg/gotenberg/pdfengine.go b/pkg/gotenberg/pdfengine.go
index a59efccf..f8eaad6e 100644
--- a/pkg/gotenberg/pdfengine.go
+++ b/pkg/gotenberg/pdfengine.go
@@ -96,8 +96,9 @@ type PdfEngine interface {
 	// Split splits a given PDF file.
 	Split(ctx context.Context, logger *zap.Logger, mode SplitMode, inputPath, outputDirPath string) ([]string, error)
 
-	// Flatten PDF refers to merging the annotations (such as markup, widgets, 3D models, etc.) into a static area that is part of the PDF document
-	// By flattening and merging existing annotation appearances with page content, the original annotations are deleted from the PDF pages.
+	// Flatten merges existing annotation appearances with page content, effectively deleting the original annotations.
+	// This process can flatten forms as well, as forms share a relationship with annotations.
+	// Note that this operation is irreversible.
 	Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error
 
 	// Convert transforms a given PDF to the specified formats defined in
diff --git a/pkg/modules/qpdf/qpdf.go b/pkg/modules/qpdf/qpdf.go
index 5b9bf5fd..82a9700d 100644
--- a/pkg/modules/qpdf/qpdf.go
+++ b/pkg/modules/qpdf/qpdf.go
@@ -101,7 +101,7 @@ func (engine *QPdf) Merge(ctx context.Context, logger *zap.Logger, inputPaths []
 	return fmt.Errorf("merge PDFs with QPDF: %w", err)
 }
 
-// Flatten is not available in this implementation.
+// Flatten merges annotation appearances with page content, deleting the original annotations.
 func (engine *QPdf) Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error {
 	var args []string
 	args = append(args, "--generate-appearances")