diff --git a/doc/interop-test-descriptions.md b/doc/interop-test-descriptions.md
index 3dd7807dec0..480625c6ba7 100644
--- a/doc/interop-test-descriptions.md
+++ b/doc/interop-test-descriptions.md
@@ -89,11 +89,10 @@ Client asserts:
 
 ### client_compressed_unary
 
-This test verifies the client can compress unary messages. It sends an initial
-inconsistent request to verify whether the server supports the
-[CompressedRequest][] feature. If it does, it should catch the inconsistency and
-fail the call with an `INVALID_ARGUMENT` status. If the feature is supported, it
-proceeds with two unary calls, for compressed and uncompressed payloads.
+This test verifies the client can compress unary messages by sending two unary
+calls, for compressed and uncompressed payloads. It sends an initial probing
+request to verify whether the server supports the [CompressedRequest][] feature.
+If it doesn't, the call is expected to fail with an `INVALID_ARGUMENT` status.
 
 Server features:
 * [UnaryCall][]
@@ -140,14 +139,14 @@ Procedure:
       calls were successful.
     * Response payload body is 314159 bytes in size.
     * Clients are free to assert that the response payload body contents are
-      zero and comparing the entire response message against a golden response.
+      zeros and comparing the entire response message against a golden response.
 
 
 ### server_compressed_unary
 
 This test verifies the server can compress unary messages. It sends two unary
-requests, expecting the server response to be
-compressed or not according to the `response_compressed` boolean.
+requests, expecting the server's response to be compressed or not according to
+the `response_compressed` boolean.
 
 Whether compression was actually performed is determined by the compression bit
 in the response's message flags.
@@ -158,7 +157,7 @@ Server features:
 * [CompressedResponse][]
 
 Procedure:
- 1. Client calls UnaryCall with:
+ 1. Client calls UnaryCall with `SimpleRequest`s:
 
     ```
     {
@@ -257,7 +256,8 @@ compressed with `expect_compressed` true; the second one uncompressed with
 
 Procedure:
  1. Client calls StreamingInputCall
- 1. Client sends the following feature-probing *uncompressed* message
+ 1. Client sends the following feature-probing *uncompressed*
+ `StreamingInputCallRequest` message
 
     ```
     {
@@ -305,7 +305,7 @@ Server features:
 * [StreamingOutputCall][]
 
 Procedure:
- 1. Client calls StreamingOutputCall with:
+ 1. Client calls StreamingOutputCall with `StreamingOutputCallRequest`:
 
     ```
     {
@@ -341,27 +341,16 @@ Server features:
 
 
 Procedure:
- 1. Client calls StreamingOutputCall with:
-
-    ```
-    {
-      response_compressed: true
-      response_parameters:{
-        size: 31415
-      }
-      response_parameters:{
-        size: 58979
-      }
-    }
-    ```
+ 1. Client calls StreamingOutputCall with `StreamingOutputCallRequest`:
 
     ```
     {
-      response_compressed: false
       response_parameters:{
+        response_compressed: true
         size: 31415
       }
       response_parameters:{
+        response_compressed: false
         size: 58979
       }
     }
diff --git a/src/proto/grpc/testing/messages.proto b/src/proto/grpc/testing/messages.proto
index 782fd40989d..1812dc74029 100644
--- a/src/proto/grpc/testing/messages.proto
+++ b/src/proto/grpc/testing/messages.proto
@@ -32,6 +32,8 @@
 
 syntax = "proto3";
 
+import "google/protobuf/wrappers.proto";
+
 package grpc.testing;
 
 // DEPRECATED, don't use. To be removed shortly.
@@ -76,8 +78,11 @@ message SimpleRequest {
   // Whether SimpleResponse should include OAuth scope.
   bool fill_oauth_scope = 5;
 
-  // Whether to request the server to compress the response.
-  bool response_compressed = 6;
+  // Whether to request the server to compress the response. This field is
+  // "nullable" in order to interoperate seamlessly with clients not able to
+  // implement the full compression tests by introspecting the call to verify
+  // the response's compression status.
+  google.protobuf.BoolValue response_compressed = 6;
 
   // Whether server should return a given status
   EchoStatus response_status = 7;
@@ -102,8 +107,11 @@ message StreamingInputCallRequest {
   // Optional input payload sent along with the request.
   Payload payload = 1;
 
-  // Whether the server should expect this request to be compressed.
-  bool expect_compressed = 2;
+  // Whether the server should expect this request to be compressed. This field
+  // is "nullable" in order to interoperate seamlessly with servers not able to
+  // implement the full compression tests by introspecting the call to verify
+  // the request's compression status.
+  BoolValue expect_compressed = 2;
 
   // Not expecting any payload from the response.
 }
@@ -122,6 +130,12 @@ message ResponseParameters {
   // Desired interval between consecutive responses in the response stream in
   // microseconds.
   int32 interval_us = 2;
+
+  // Whether to request the server to compress the response. This field is
+  // "nullable" in order to interoperate seamlessly with clients not able to
+  // implement the full compression tests by introspecting the call to verify
+  // the response's compression status.
+  BoolValue compressed = 3;
 }
 
 // Server-streaming request.
@@ -139,9 +153,6 @@ message StreamingOutputCallRequest {
   // Optional input payload sent along with the request.
   Payload payload = 3;
 
-  // Whether to request the server to compress the response.
-  bool response_compressed = 6;
-
   // Whether server should return a given status
   EchoStatus response_status = 7;
 }