diff --git a/README.md b/README.md
index 0e894eb..025c3e7 100644
--- a/README.md
+++ b/README.md
@@ -31,13 +31,17 @@ Usage: dinglehopper [OPTIONS] GT OCR [REPORT_PREFIX]
 
   Compare the PAGE/ALTO/text document GT against the document OCR.
 
+  dinglehopper detects if GT/OCR are ALTO or PAGE XML documents to extract
+  their text and falls back to plain text if no ALTO or PAGE is detected.
+
   The files GT and OCR are usually a ground truth document and the result of
   an OCR software, but you may use dinglehopper to compare two OCR results.
   In that case, use --no-metrics to disable the then meaningless metrics and
   also change the color scheme from green/red to blue.
 
   The comparison report will be written to $REPORT_PREFIX.{html,json}, where
-  $REPORT_PREFIX defaults to "report".
+  $REPORT_PREFIX defaults to "report". The reports include the character
+  error rate (CER) and the word error rate (WER).
 
 Options:
   --metrics / --no-metrics  Enable/disable metrics and green/red
diff --git a/qurator/dinglehopper/cli.py b/qurator/dinglehopper/cli.py
index 1e53a94..759d040 100644
--- a/qurator/dinglehopper/cli.py
+++ b/qurator/dinglehopper/cli.py
@@ -105,13 +105,17 @@ def main(gt, ocr, report_prefix, metrics):
     """
     Compare the PAGE/ALTO/text document GT against the document OCR.
 
+    dinglehopper detects if GT/OCR are ALTO or PAGE XML documents to extract
+    their text and falls back to plain text if no ALTO or PAGE is detected.
+
     The files GT and OCR are usually a ground truth document and the result of
     an OCR software, but you may use dinglehopper to compare two OCR results. In
     that case, use --no-metrics to disable the then meaningless metrics and also
     change the color scheme from green/red to blue.
 
     The comparison report will be written to $REPORT_PREFIX.{html,json}, where
-    $REPORT_PREFIX defaults to "report".
+    $REPORT_PREFIX defaults to "report". The reports include the character error
+    rate (CER) and the word error rate (WER).
     """
     process(gt, ocr, report_prefix, metrics=metrics)