diff --git a/Directory.Build.props b/Directory.Build.props
index 59ed3a3..83b1ab4 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -1,5 +1,5 @@
 <Project>
   <PropertyGroup>
-    <Version>0.3.3</Version>
+    <Version>0.3.4</Version>
   </PropertyGroup>
 </Project>
\ No newline at end of file
diff --git a/src/QAToolKit.Engine.HttpTester.Test/Exceptions/QAToolKitEngineHttpTesterExceptionTests.cs b/src/QAToolKit.Engine.HttpTester.Test/Exceptions/QAToolKitEngineHttpTesterExceptionTests.cs
index 0fdd524..74247c9 100644
--- a/src/QAToolKit.Engine.HttpTester.Test/Exceptions/QAToolKitEngineHttpTesterExceptionTests.cs
+++ b/src/QAToolKit.Engine.HttpTester.Test/Exceptions/QAToolKitEngineHttpTesterExceptionTests.cs
@@ -1,6 +1,5 @@
 using QAToolKit.Engine.HttpTester.Exceptions;
 using System;
-using System.Runtime.Serialization;
 using Xunit;
 
 namespace QAToolKit.Engine.HttpTester.Test.Exceptions
diff --git a/src/QAToolKit.Engine.HttpTester.Test/HttpTestAsserterTests.cs b/src/QAToolKit.Engine.HttpTester.Test/HttpTestAsserterTests.cs
index 581f806..6919688 100644
--- a/src/QAToolKit.Engine.HttpTester.Test/HttpTestAsserterTests.cs
+++ b/src/QAToolKit.Engine.HttpTester.Test/HttpTestAsserterTests.cs
@@ -5,13 +5,11 @@
 using System.Linq;
 using System.Net;
 using System.Net.Http;
-using System.Net.Http.Headers;
-using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using Xunit;
 
 namespace QAToolKit.Engine.HttpTester.Test
-{
+{ 
     public class HttpTestAsserterTests
     {
         [Fact]
@@ -120,7 +118,7 @@ public async Task HttpTestAsserterHeaderMissing_Fails()
                 var httpDuration = client.HttpDuration;
                 Assert.Throws<ArgumentNullException>(() => asserter
                     .ResponseContentContains("scott")
-                    .RequestDurationEquals(duration, (x) => x < 2000)
+                    .RequestDurationEquals(duration, (x) => x < Convert.ToInt64("2000"), "x < 2000")
                     .RequestDurationEquals(httpDuration, (x) => x < 1800)
                     .ResponseStatusCodeEquals(HttpStatusCode.OK)
                     .ResponseContentTypeEquals("application/json")
diff --git a/src/QAToolKit.Engine.HttpTester/Exceptions/QAToolKitEngineHttpTesterException.cs b/src/QAToolKit.Engine.HttpTester/Exceptions/QAToolKitEngineHttpTesterException.cs
index f050139..e3814ba 100644
--- a/src/QAToolKit.Engine.HttpTester/Exceptions/QAToolKitEngineHttpTesterException.cs
+++ b/src/QAToolKit.Engine.HttpTester/Exceptions/QAToolKitEngineHttpTesterException.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Runtime.Serialization;
 
 namespace QAToolKit.Engine.HttpTester.Exceptions
 {
diff --git a/src/QAToolKit.Engine.HttpTester/HttpTestAsserter.cs b/src/QAToolKit.Engine.HttpTester/HttpTestAsserter.cs
index 776ffb1..ec3aa55 100644
--- a/src/QAToolKit.Engine.HttpTester/HttpTestAsserter.cs
+++ b/src/QAToolKit.Engine.HttpTester/HttpTestAsserter.cs
@@ -3,6 +3,7 @@
 using QAToolKit.Engine.HttpTester.Models;
 using System;
 using System.Collections.Generic;
+using System.Linq.Expressions;
 using System.Net;
 using System.Net.Http;
 using System.Net.Http.Headers;
@@ -24,7 +25,8 @@ public class HttpTestAsserter : IHttpTestAsserter
         /// <param name="httpResponseMessage"></param>
         public HttpTestAsserter(HttpResponseMessage httpResponseMessage)
         {
-            _httpResponseMessage = httpResponseMessage ?? throw new ArgumentNullException($"{nameof(httpResponseMessage)} is null.");
+            _httpResponseMessage = httpResponseMessage ??
+                                   throw new ArgumentNullException($"{nameof(httpResponseMessage)} is null.");
             _assertResults = new List<AssertResult>();
         }
 
@@ -40,8 +42,8 @@ public IEnumerable<AssertResult> AssertAll()
         /// <summary>
         /// HTTP body contains a string (ignores case)
         /// </summary>
-        /// <param name="keyword"></param>
-        /// <param name="caseInsensitive"></param>
+        /// <param name="keyword">Check if the HTTP response body contains a keyword.</param>
+        /// <param name="caseInsensitive">Use case sensitive string comparison.</param>
         /// <returns></returns>
         public IHttpTestAsserter ResponseContentContains(string keyword, bool caseInsensitive = true)
         {
@@ -52,20 +54,27 @@ public IHttpTestAsserter ResponseContentContains(string keyword, bool caseInsens
 
             var bodyString = _httpResponseMessage.Content.ReadAsStringAsync().GetAwaiter().GetResult();
 
-            _assertResults.Add(new AssertResult()
+            var assertResult = new AssertResult()
             {
-                Name = nameof(ResponseContentContains),
-                Message = $"Body contains '{keyword}'.",
-                IsTrue = caseInsensitive ? StringHelper.ContainsCaseInsensitive(bodyString, keyword) : bodyString.Contains(keyword)
-            });
+                Name = nameof(ResponseContentContains)
+            };
+
+            assertResult.IsTrue = caseInsensitive
+                ? StringHelper.ContainsCaseInsensitive(bodyString, keyword)
+                : bodyString.Contains(keyword);
+            assertResult.Message = assertResult.IsTrue
+                ? $"Response body contains keyword '{keyword}'."
+                : $"Response body does not contain keyword '{keyword}'.";
+
+            _assertResults.Add(assertResult);
 
             return this;
         }
-        
+
         /// <summary>
         /// Check if the response contains specified Content Type
         /// </summary>
-        /// <param name="contentType"></param>
+        /// <param name="contentType">Check if the response content type equals the parameter.</param>
         /// <returns></returns>
         /// <exception cref="ArgumentNullException"></exception>
         public IHttpTestAsserter ResponseContentTypeEquals(string contentType)
@@ -75,12 +84,12 @@ public IHttpTestAsserter ResponseContentTypeEquals(string contentType)
                 throw new ArgumentNullException($"{nameof(contentType)} is null.");
             }
 
-            var bodyString = _httpResponseMessage.Content.Headers.ContentType;
-  
+            var responseContentType = _httpResponseMessage.Content.Headers.ContentType.MediaType;
+
             _assertResults.Add(new AssertResult()
             {
                 Name = nameof(ResponseContentTypeEquals),
-                Message = $"Response content-type equals '{contentType}'.",
+                Message = $"Expected content-type = '{contentType}', actual = '{responseContentType}'.",
                 IsTrue = _httpResponseMessage.Content.Headers.ContentType.MediaType == contentType
             });
 
@@ -90,18 +99,44 @@ public IHttpTestAsserter ResponseContentTypeEquals(string contentType)
         /// <summary>
         /// Verify request duration
         /// </summary>
-        /// <param name="duration"></param>
-        /// <param name="predicateFunction"></param>
+        /// <param name="duration">Actual duration of the HTTP request execution</param>
+        /// <param name="predicateFunction">It's a function that validates the duration</param>
+        /// <param name="predicateFunctionExpression">String predicateFunctionExpression for the report. If set it will be used in the assert result message.</param>
         /// <returns></returns>
-        public IHttpTestAsserter RequestDurationEquals(long duration, Func<long, bool> predicateFunction)
+        public IHttpTestAsserter RequestDurationEquals(long duration, Expression<Func<long, bool>> predicateFunction, string predicateFunctionExpression = null)
         {
-            var isTrue = predicateFunction.Invoke(duration);
-            _assertResults.Add(new AssertResult()
+            var isTrue = predicateFunction.Compile()(duration);
+
+            var assertResult = new AssertResult()
             {
                 Name = nameof(RequestDurationEquals),
-                Message = $"Duration is '{duration}'.",
                 IsTrue = isTrue
-            });
+            };
+
+            if (isTrue)
+            {
+                if (string.IsNullOrEmpty(predicateFunctionExpression))
+                {
+                    assertResult.Message = $"Duration is '{duration}ms' and is valid.";
+                }
+                else
+                {
+                    assertResult.Message = $"Duration is '{duration}ms' and is valid with predicateFunctionExpression '{predicateFunctionExpression}'.";
+                }
+            }
+            else
+            {
+                if (string.IsNullOrEmpty(predicateFunctionExpression))
+                {
+                    assertResult.Message = $"Duration is '{duration}ms' and is invalid.";
+                }
+                else
+                {
+                    assertResult.Message = $"Duration is '{duration}ms' and is invalid with predicateFunctionExpression '{predicateFunctionExpression}'.";
+                }
+            }
+            
+            _assertResults.Add(assertResult);
 
             return this;
         }
@@ -109,7 +144,7 @@ public IHttpTestAsserter RequestDurationEquals(long duration, Func<long, bool> p
         /// <summary>
         /// HTTP response contains a header
         /// </summary>
-        /// <param name="headerName"></param>
+        /// <param name="headerName">Check if the HTTP response contains the header with the name.</param>
         /// <returns></returns>
         public IHttpTestAsserter ResponseHasHttpHeader(string headerName)
         {
@@ -118,12 +153,17 @@ public IHttpTestAsserter ResponseHasHttpHeader(string headerName)
                 throw new ArgumentNullException($"{nameof(headerName)} is null.");
             }
 
-            _assertResults.Add(new AssertResult()
+            var assertResult = new AssertResult
             {
                 Name = nameof(ResponseHasHttpHeader),
-                Message = $"Contains header '{headerName}'.",
                 IsTrue = _httpResponseMessage.Headers.TryGetValues(headerName, out var values)
-            });
+            };
+
+            assertResult.Message = assertResult.IsTrue
+                ? $"Response message contains header '{headerName}'."
+                : $"Response message does not contain header '{headerName}'.";
+
+            _assertResults.Add(assertResult);
 
             return this;
         }
@@ -131,14 +171,15 @@ public IHttpTestAsserter ResponseHasHttpHeader(string headerName)
         /// <summary>
         /// Verify if response code equals
         /// </summary>
-        /// <param name="httpStatusCode"></param>
+        /// <param name="httpStatusCode">Check if the HTTP response status code equals to this parameter.</param>
         /// <returns></returns>
         public IHttpTestAsserter ResponseStatusCodeEquals(HttpStatusCode httpStatusCode)
         {
             _assertResults.Add(new AssertResult()
             {
                 Name = nameof(ResponseStatusCodeEquals),
-                Message = $"Expected status code is '{httpStatusCode}' return code is '{_httpResponseMessage.StatusCode}'.",
+                Message =
+                    $"Expected status code = '{httpStatusCode}', actual = '{_httpResponseMessage.StatusCode}'.",
                 IsTrue = _httpResponseMessage.StatusCode == httpStatusCode
             });
 
@@ -154,7 +195,7 @@ public IHttpTestAsserter ResponseStatusCodeIsSuccess()
             _assertResults.Add(new AssertResult()
             {
                 Name = nameof(ResponseStatusCodeIsSuccess),
-                Message = $"Expected status code is '2xx' return code is '{_httpResponseMessage.StatusCode}'.",
+                Message = $"Expected status code = '2xx', actual = '{_httpResponseMessage.StatusCode}'.",
                 IsTrue = _httpResponseMessage.IsSuccessStatusCode
             });
 
@@ -172,11 +213,11 @@ public IHttpTestAsserter ResponseBodyIsEmpty()
             _assertResults.Add(new AssertResult()
             {
                 Name = nameof(ResponseBodyIsEmpty),
-                Message = $"Expected empty body, returned body is '{bodyString}'.",
+                Message = $"Expected empty response body, actual = '{bodyString}'.",
                 IsTrue = string.IsNullOrEmpty(bodyString)
             });
 
             return this;
         }
     }
-}
+}
\ No newline at end of file
diff --git a/src/QAToolKit.Engine.HttpTester/Interfaces/IHttpTestAsserter.cs b/src/QAToolKit.Engine.HttpTester/Interfaces/IHttpTestAsserter.cs
index d621001..e9e1446 100644
--- a/src/QAToolKit.Engine.HttpTester/Interfaces/IHttpTestAsserter.cs
+++ b/src/QAToolKit.Engine.HttpTester/Interfaces/IHttpTestAsserter.cs
@@ -1,6 +1,7 @@
 using QAToolKit.Engine.HttpTester.Models;
 using System;
 using System.Collections.Generic;
+using System.Linq.Expressions;
 using System.Net;
 using System.Net.Http.Headers;
 
@@ -18,13 +19,15 @@ public interface IHttpTestAsserter
         /// <param name="caseInsensitive"></param>
         /// <returns></returns>
         IHttpTestAsserter ResponseContentContains(string keyword, bool caseInsensitive = true);
+
         /// <summary>
         /// Verify request duration
         /// </summary>
         /// <param name="duration"></param>
         /// <param name="predicateFunction"></param>
+        /// <param name="predicateFunctionExpression"></param>
         /// <returns></returns>
-        IHttpTestAsserter RequestDurationEquals(long duration, Func<long, bool> predicateFunction);
+        IHttpTestAsserter RequestDurationEquals(long duration, Expression<Func<long, bool>> predicateFunction, string predicateFunctionExpression = null);
         /// <summary>
         /// Verify if response code equals
         /// </summary>