diff --git a/tools/test-bots b/tools/test-bots
index 571f6b7..0ef8429 100755
--- a/tools/test-bots
+++ b/tools/test-bots
@@ -20,6 +20,8 @@ def load_tests_from_modules(names, template):
 
 def load_all_tests():
     loader = unittest.defaultTestLoader
+    # Codecov seems to work only when using loader.discover. It failed to capture line executions
+    # for functions like loader.loadTestFromModule or loader.loadTestFromNames.
     return loader.discover('zulip_bots')
 
 def parse_args(available_bots):
diff --git a/tools/test-botserver b/tools/test-botserver
index 58444a0..f6bf561 100755
--- a/tools/test-botserver
+++ b/tools/test-botserver
@@ -26,6 +26,8 @@ def main():
             cov.load()
         cov.start()
 
+    # Codecov seems to work only when using loader.discover. It failed to capture line executions
+    # for functions like loader.loadTestFromModule or loader.loadTestFromNames.
     test_suites = unittest.defaultTestLoader.discover('zulip_botserver')
     suite = unittest.TestSuite(test_suites)
     runner = unittest.TextTestRunner(verbosity=2)