1 files changed, 5 insertions, 0 deletions
diff --git a/src/csharp/Grpc.Core/Call.cs b/src/csharp/Grpc.Core/Call.cs
index fe5f40f5e9..771cc083da 100644
--- a/src/csharp/Grpc.Core/Call.cs
+++ b/src/csharp/Grpc.Core/Call.cs
@@ -37,7 +37,12 @@ using Grpc.Core.Utils;
 
 namespace Grpc.Core
 {
+    /// <summary>
+    /// Abstraction of a call to be invoked on a client.
+    /// </summary>
     public class Call<TRequest, TResponse>
+        where TRequest : class
+        where TResponse : class
     {
         readonly string name;
         readonly Marshaller<TRequest> requestMarshaller;