diff --git a/xtool/env/llvm/llvm.go b/xtool/env/llvm/llvm.go
index 6bea3099..56771908 100644
--- a/xtool/env/llvm/llvm.go
+++ b/xtool/env/llvm/llvm.go
@@ -38,6 +38,9 @@ const (
 
 // -----------------------------------------------------------------------------
 
+// defaultLLVMConfigBin returns the default path to the llvm-config binary. It
+// checks the LLVM_CONFIG environment variable first, then searches in PATH. If
+// not found, it returns [ldLLVMConfigBin] as a last resort.
 func defaultLLVMConfigBin() string {
 	bin := os.Getenv("LLVM_CONFIG")
 	if bin != "" {