diff --git a/rule/morph-fast-apply.md b/rule/morph-fast-apply.md
index 0c1ddcd..d4af44c 100644
--- a/rule/morph-fast-apply.md
+++ b/rule/morph-fast-apply.md
@@ -1,3 +1,10 @@
+---
+description: >
+  IMPORTANT: Always prefer `morph_edit` over `edit` (string replace) or full file
+  writes when modifying existing files. `morph_edit` works with partial code
+  snippets and does NOT require full file content.
+---
+
 # Morph Fast Apply - Tool Selection Guide
 
 When editing code files, choose the appropriate tool based on the situation: