diff --git a/api/types/descriptor/descriptor.proto b/api/types/descriptor/descriptor.proto
index 7a82bd8..99c8ada 100644
--- a/api/types/descriptor/descriptor.proto
+++ b/api/types/descriptor/descriptor.proto
@@ -4,6 +4,11 @@ package containerd.v1.types;
 
 import "gogoproto/gogo.proto";
 
+// Descriptor describes a blob in a content store.
+//
+// This descriptor can be used to reference content from an
+// oci descriptor found in a manifest.
+// See https://godoc.org/github.com/opencontainers/image-spec/specs-go/v1#Descriptor
 message Descriptor {
 	string mediaType = 1;
 	string digest = 2 [(gogoproto.customtype) = "github.com/opencontainers/go-digest.Digest", (gogoproto.nullable) = false];
diff --git a/rootfs/init.go b/rootfs/init.go
index e2fe777..ebcae81 100644
--- a/rootfs/init.go
+++ b/rootfs/init.go
@@ -24,7 +24,7 @@ func InitRootFS(ctx context.Context, name string, parent digest.Digest, readonly
 	if err == nil {
 		return nil, errors.Errorf("rootfs already exists")
 	}
-	// TODO: check if should return error
+	// TODO: ensure not exist error once added to snapshot package
 
 	parentS := parent.String()
 
@@ -53,7 +53,7 @@ func createInitLayer(ctx context.Context, parent, initName string, initFn func(s
 	if _, err := snapshotter.Stat(ctx, initS); err == nil {
 		return initS, nil
 	}
-	// TODO: check if should return error
+	// TODO: ensure not exist error once added to snapshot package
 
 	// Create tempdir
 	td, err := ioutil.TempDir("", "create-init-")