diff --git a/Android.bp b/Android.bp
index 6c9bdd348d..7ae00b66ac 100644
--- a/Android.bp
+++ b/Android.bp
@@ -10,15 +10,21 @@ cc_defaults {
     ],
 }
 
+// VTS tests must link to HAL definition libraries statically.
 cc_defaults {
     name: "VtsHalTargetTestDefaults",
     defaults: ["hidl_defaults"],
+
+    // Lists all dependencies that can *not* be expected on the device.
     static_libs: [
         "VtsHalHidlTargetTestBase",
     ],
     group_static_libs: true,
+
+    // Lists all system dependencies that can be expected on the device.
     shared_libs: [
         "libbase",
+        // All the following are dependencies of any HAL definition library.
         "libcutils",
         "liblog",
         "libhidlbase",