diff --git a/internal/shell/shell.go b/internal/shell/shell.go
index 580ab3c5d592f6e2f41bbf65dfea6990d3b35b2f..aabd79f2082ea96e43ac9f4bb4f36f31ad743961 100644
--- a/internal/shell/shell.go
+++ b/internal/shell/shell.go
@@ -82,6 +82,14 @@ func NewShell(opts *Options) *Shell {
 		env = os.Environ()
 	}
 
+	// Allow tools to detect execution by Crush.
+	env = append(
+		env,
+		"CRUSH=1",
+		"AGENT=crush",
+		"AI_AGENT=crush",
+	)
+
 	logger := opts.Logger
 	if logger == nil {
 		logger = noopLogger{}