diff --git a/build/toolchain/android/BUILD.gn b/build/toolchain/android/BUILD.gn
index 285f2d7ff1..cb1d95da6f 100644
--- a/build/toolchain/android/BUILD.gn
+++ b/build/toolchain/android/BUILD.gn
@@ -178,6 +178,10 @@ android_gcc_toolchains_helper("arm64") {
   toolchain_cpu = "aarch64"
 }
 
+# This toolchain should only be used to build the target
+# //third_party/vulkan_validation_layers. This is because vulkan validation
+# layers requires API level >= 26, but Flutter officially supports down to API
+# level 22, which is the default value of the android_api_level argument.
 android_gcc_toolchains_helper("arm64_apilevel26") {
   android_ndk_lib_dir = arm64_android_lib