diff --git a/packages/opencode/src/tool/question.txt b/packages/opencode/src/tool/question.txt
index a85a4110f50..dfe34134704 100644
--- a/packages/opencode/src/tool/question.txt
+++ b/packages/opencode/src/tool/question.txt
@@ -8,3 +8,4 @@ Usage notes:
 - Users will always be able to select "Other" to provide custom text input
 - Answers are returned as arrays of labels; set `multiple: true` to allow selecting more than one
 - If you recommend a specific option, make that the first option in the list and add "(Recommended)" at the end of the label
+- The `header` propery accepts a maximum of 12 characters per header