diff --git a/xonsh/environ.py b/xonsh/environ.py
index 6cd232c2c..f664069ad 100644
--- a/xonsh/environ.py
+++ b/xonsh/environ.py
@@ -379,6 +379,9 @@ def DEFAULT_DOCS():
         'with Bash, xonsh always prefer an existing relative path.'),
     'COLOR_INPUT': VarDocs('Flag for syntax highlighting interactive input.'),
     'COLOR_RESULTS': VarDocs('Flag for syntax highlighting return values.'),
+    'COMPLETIONS_BRACKETS': VarDocs(
+        'Flag to enable/disable inclusion of square brackets and parentheses '
+        'in Python attribute completions.', default='True'),
     'COMPLETIONS_DISPLAY': VarDocs(
         'Configure if and how Python completions are displayed by the '
         'prompt_toolkit shell.\n\nThis option does not affect Bash '