diff --git a/pkg/tool/exec/exec.cue b/pkg/tool/exec/exec.cue
index c98008371b2..ee77df3a8b0 100644
--- a/pkg/tool/exec/exec.cue
+++ b/pkg/tool/exec/exec.cue
@@ -19,6 +19,8 @@ Run: {
 	$id: *"tool/exec.Run" | "exec" // exec for backwards compatibility
 
 	// cmd is the command to run.
+	// Simple commands can use a string, which is split by white space characters.
+	// If any arguments include white space, use the list form.
 	cmd: string | [string, ...string]
 
 	// dir specifies the working directory of the command.
diff --git a/pkg/tool/exec/pkg.go b/pkg/tool/exec/pkg.go
index c20f7299ab3..c8c968dd082 100644
--- a/pkg/tool/exec/pkg.go
+++ b/pkg/tool/exec/pkg.go
@@ -9,6 +9,8 @@
 //		$id: *"tool/exec.Run" | "exec" // exec for backwards compatibility
 //
 //		// cmd is the command to run.
+//		// Simple commands can use a string, which is split by white space characters.
+//		// If any arguments include white space, use the list form.
 //		cmd: string | [string, ...string]
 //
 //		// dir specifies the working directory of the command.