diff --git a/README.md b/README.md
index d9a277c2..f5bf7f4f 100644
--- a/README.md
+++ b/README.md
@@ -306,7 +306,7 @@ public class MyHook : Hook
     // code to run if there's an error during before hooks or during flag evaluation
   }
 
-  public ValueTask FinallyAsync<T>(HookContext<T> context, IReadOnlyDictionary<string, object> hints = null)
+  public ValueTask FinallyAsync<T>(HookContext<T> context, FlagEvaluationDetails<T> evaluationDetails, IReadOnlyDictionary<string, object> hints = null)
   {
     // code to run after all other stages, regardless of success/failure
   }
diff --git a/src/OpenFeature/Hook.cs b/src/OpenFeature/Hook.cs
index aea5dc15..c1dbbe38 100644
--- a/src/OpenFeature/Hook.cs
+++ b/src/OpenFeature/Hook.cs
@@ -31,7 +31,8 @@ public abstract class Hook
         /// <typeparam name="T">Flag value type (bool|number|string|object)</typeparam>
         /// <returns>Modified EvaluationContext that is used for the flag evaluation</returns>
         public virtual ValueTask<EvaluationContext> BeforeAsync<T>(HookContext<T> context,
-            IReadOnlyDictionary<string, object>? hints = null, CancellationToken cancellationToken = default)
+            IReadOnlyDictionary<string, object>? hints = null,
+            CancellationToken cancellationToken = default)
         {
             return new ValueTask<EvaluationContext>(EvaluationContext.Empty);
         }
@@ -44,8 +45,10 @@ public virtual ValueTask<EvaluationContext> BeforeAsync<T>(HookContext<T> contex
         /// <param name="hints">Caller provided data</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/>.</param>
         /// <typeparam name="T">Flag value type (bool|number|string|object)</typeparam>
-        public virtual ValueTask AfterAsync<T>(HookContext<T> context, FlagEvaluationDetails<T> details,
-            IReadOnlyDictionary<string, object>? hints = null, CancellationToken cancellationToken = default)
+        public virtual ValueTask AfterAsync<T>(HookContext<T> context,
+            FlagEvaluationDetails<T> details,
+            IReadOnlyDictionary<string, object>? hints = null,
+            CancellationToken cancellationToken = default)
         {
             return new ValueTask();
         }
@@ -58,8 +61,10 @@ public virtual ValueTask AfterAsync<T>(HookContext<T> context, FlagEvaluationDet
         /// <param name="hints">Caller provided data</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/>.</param>
         /// <typeparam name="T">Flag value type (bool|number|string|object)</typeparam>
-        public virtual ValueTask ErrorAsync<T>(HookContext<T> context, Exception error,
-            IReadOnlyDictionary<string, object>? hints = null, CancellationToken cancellationToken = default)
+        public virtual ValueTask ErrorAsync<T>(HookContext<T> context,
+            Exception error,
+            IReadOnlyDictionary<string, object>? hints = null,
+            CancellationToken cancellationToken = default)
         {
             return new ValueTask();
         }
@@ -68,10 +73,14 @@ public virtual ValueTask ErrorAsync<T>(HookContext<T> context, Exception error,
         /// Called unconditionally after flag evaluation.
         /// </summary>
         /// <param name="context">Provides context of innovation</param>
+        /// <param name="evaluationDetails">Flag evaluation information</param>
         /// <param name="hints">Caller provided data</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/>.</param>
         /// <typeparam name="T">Flag value type (bool|number|string|object)</typeparam>
-        public virtual ValueTask FinallyAsync<T>(HookContext<T> context, IReadOnlyDictionary<string, object>? hints = null, CancellationToken cancellationToken = default)
+        public virtual ValueTask FinallyAsync<T>(HookContext<T> context,
+            FlagEvaluationDetails<T> evaluationDetails,
+            IReadOnlyDictionary<string, object>? hints = null,
+            CancellationToken cancellationToken = default)
         {
             return new ValueTask();
         }
diff --git a/src/OpenFeature/OpenFeatureClient.cs b/src/OpenFeature/OpenFeatureClient.cs
index e774c6b5..787c89ee 100644
--- a/src/OpenFeature/OpenFeatureClient.cs
+++ b/src/OpenFeature/OpenFeatureClient.cs
@@ -244,7 +244,7 @@ private async Task<FlagEvaluationDetails<T>> EvaluateFlagAsync<T>(
                 evaluationContextBuilder.Build()
             );
 
-            FlagEvaluationDetails<T> evaluation;
+            FlagEvaluationDetails<T>? evaluation = null;
             try
             {
                 var contextFromHooks = await this.TriggerBeforeHooksAsync(allHooks, hookContext, options, cancellationToken).ConfigureAwait(false);
@@ -297,7 +297,9 @@ await this.TriggerErrorHooksAsync(allHooksReversed, hookContext, exception, opti
             }
             finally
             {
-                await this.TriggerFinallyHooksAsync(allHooksReversed, hookContext, options, cancellationToken).ConfigureAwait(false);
+                evaluation ??= new FlagEvaluationDetails<T>(flagKey, defaultValue, ErrorType.General, Reason.Error, string.Empty,
+                    "Evaluation failed to return a result.");
+                await this.TriggerFinallyHooksAsync(allHooksReversed, evaluation, hookContext, options, cancellationToken).ConfigureAwait(false);
             }
 
             return evaluation;
@@ -351,14 +353,14 @@ private async Task TriggerErrorHooksAsync<T>(IReadOnlyList<Hook> hooks, HookCont
             }
         }
 
-        private async Task TriggerFinallyHooksAsync<T>(IReadOnlyList<Hook> hooks, HookContext<T> context,
-            FlagEvaluationOptions? options, CancellationToken cancellationToken = default)
+        private async Task TriggerFinallyHooksAsync<T>(IReadOnlyList<Hook> hooks, FlagEvaluationDetails<T> evaluation,
+            HookContext<T> context, FlagEvaluationOptions? options, CancellationToken cancellationToken = default)
         {
             foreach (var hook in hooks)
             {
                 try
                 {
-                    await hook.FinallyAsync(context, options?.HookHints, cancellationToken).ConfigureAwait(false);
+                    await hook.FinallyAsync(context, evaluation, options?.HookHints, cancellationToken).ConfigureAwait(false);
                 }
                 catch (Exception e)
                 {
diff --git a/test/OpenFeature.Tests/OpenFeatureClientTests.cs b/test/OpenFeature.Tests/OpenFeatureClientTests.cs
index 13d3fa93..1cab2d76 100644
--- a/test/OpenFeature.Tests/OpenFeatureClientTests.cs
+++ b/test/OpenFeature.Tests/OpenFeatureClientTests.cs
@@ -656,5 +656,25 @@ public async Task TheClient_MergesTheEvaluationContextInTheCorrectOrder(string k
 
             Assert.Equal(expectedResult, actualEvaluationContext.GetValue(key).AsString);
         }
+
+        [Fact]
+        [Specification("4.3.8", "'evaluation details' passed to the 'finally' stage matches the evaluation details returned to the application author")]
+        public async Task FinallyHook_IncludesEvaluationDetails()
+        {
+            // Arrange
+            var provider = new TestProvider();
+            var providerHook = Substitute.For<Hook>();
+            provider.AddHook(providerHook);
+            await Api.Instance.SetProviderAsync(provider);
+            var client = Api.Instance.GetClient();
+
+            const string flagName = "flagName";
+
+            // Act
+            var evaluationDetails = await client.GetBooleanDetailsAsync(flagName, true);
+
+            // Assert
+            await providerHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), evaluationDetails);
+        }
     }
 }
diff --git a/test/OpenFeature.Tests/OpenFeatureHookTests.cs b/test/OpenFeature.Tests/OpenFeatureHookTests.cs
index cc8b08a1..48de5ee5 100644
--- a/test/OpenFeature.Tests/OpenFeatureHookTests.cs
+++ b/test/OpenFeature.Tests/OpenFeatureHookTests.cs
@@ -45,10 +45,10 @@ public async Task Hooks_Should_Be_Called_In_Order()
             invocationHook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
             clientHook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
             apiHook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
-            providerHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
-            invocationHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
-            clientHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
-            apiHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
+            providerHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
+            invocationHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
+            clientHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
+            apiHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>()).Returns(new ValueTask());
 
             var testProvider = new TestProvider();
             testProvider.AddHook(providerHook);
@@ -70,10 +70,10 @@ await client.GetBooleanValueAsync(flagName, defaultValue, EvaluationContext.Empt
                 invocationHook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
                 clientHook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
                 apiHook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
-                providerHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
-                invocationHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
-                clientHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
-                apiHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
+                providerHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
+                invocationHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
+                clientHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
+                apiHook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
             });
 
             _ = apiHook.Received(1).BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
@@ -84,10 +84,10 @@ await client.GetBooleanValueAsync(flagName, defaultValue, EvaluationContext.Empt
             _ = invocationHook.Received(1).AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
             _ = clientHook.Received(1).AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
             _ = apiHook.Received(1).AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
-            _ = providerHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
-            _ = invocationHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
-            _ = clientHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
-            _ = apiHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
+            _ = providerHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
+            _ = invocationHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
+            _ = clientHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
+            _ = apiHook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<IReadOnlyDictionary<string, object>>());
         }
 
         [Fact]
@@ -239,10 +239,12 @@ public async Task Hook_Should_Return_No_Errors()
             };
             var hookContext = new HookContext<bool>("test", false, FlagValueType.Boolean,
                 new ClientMetadata(null, null), new Metadata(null), EvaluationContext.Empty);
+            var evaluationDetails =
+                new FlagEvaluationDetails<bool>("test", false, ErrorType.None, "testing", "testing");
 
             await hook.BeforeAsync(hookContext, hookHints);
-            await hook.AfterAsync(hookContext, new FlagEvaluationDetails<bool>("test", false, ErrorType.None, "testing", "testing"), hookHints);
-            await hook.FinallyAsync(hookContext, hookHints);
+            await hook.AfterAsync(hookContext, evaluationDetails, hookHints);
+            await hook.FinallyAsync(hookContext, evaluationDetails, hookHints);
             await hook.ErrorAsync(hookContext, new Exception(), hookHints);
 
             hookContext.ClientMetadata.Name.Should().BeNull();
@@ -269,7 +271,7 @@ public async Task Hook_Should_Execute_In_Correct_Order()
             hook.BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>()).Returns(EvaluationContext.Empty);
             featureProvider.ResolveBooleanValueAsync(Arg.Any<string>(), Arg.Any<bool>(), Arg.Any<EvaluationContext>()).Returns(new ResolutionDetails<bool>("test", false));
             _ = hook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>());
-            _ = hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>());
+            _ = hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>());
 
             await Api.Instance.SetProviderAsync(featureProvider);
             var client = Api.Instance.GetClient();
@@ -282,12 +284,12 @@ public async Task Hook_Should_Execute_In_Correct_Order()
                 hook.BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>());
                 featureProvider.ResolveBooleanValueAsync(Arg.Any<string>(), Arg.Any<bool>(), Arg.Any<EvaluationContext>());
                 hook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>());
-                hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>());
+                hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>());
             });
 
             _ = hook.Received(1).BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>());
             _ = hook.Received(1).AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>());
-            _ = hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>());
+            _ = hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>());
             _ = featureProvider.Received(1).ResolveBooleanValueAsync(Arg.Any<string>(), Arg.Any<bool>(), Arg.Any<EvaluationContext>());
         }
 
@@ -331,8 +333,8 @@ public async Task Finally_Hook_Should_Be_Executed_Even_If_Abnormal_Termination()
             featureProvider.ResolveBooleanValueAsync(Arg.Any<string>(), Arg.Any<bool>(), Arg.Any<EvaluationContext>()).Returns(new ResolutionDetails<bool>("test", false));
             hook2.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null).Returns(new ValueTask());
             hook1.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null).Returns(new ValueTask());
-            hook2.FinallyAsync(Arg.Any<HookContext<bool>>(), null).Returns(new ValueTask());
-            hook1.FinallyAsync(Arg.Any<HookContext<bool>>(), null).Throws(new Exception());
+            hook2.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null).Returns(new ValueTask());
+            hook1.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null).Throws(new Exception());
 
             await Api.Instance.SetProviderAsync(featureProvider);
             var client = Api.Instance.GetClient();
@@ -348,8 +350,8 @@ public async Task Finally_Hook_Should_Be_Executed_Even_If_Abnormal_Termination()
                 featureProvider.ResolveBooleanValueAsync(Arg.Any<string>(), Arg.Any<bool>(), Arg.Any<EvaluationContext>());
                 hook2.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
                 hook1.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
-                hook2.FinallyAsync(Arg.Any<HookContext<bool>>(), null);
-                hook1.FinallyAsync(Arg.Any<HookContext<bool>>(), null);
+                hook2.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
+                hook1.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
             });
 
             _ = hook1.Received(1).BeforeAsync(Arg.Any<HookContext<bool>>(), null);
@@ -357,8 +359,8 @@ public async Task Finally_Hook_Should_Be_Executed_Even_If_Abnormal_Termination()
             _ = featureProvider.Received(1).ResolveBooleanValueAsync(Arg.Any<string>(), Arg.Any<bool>(), Arg.Any<EvaluationContext>());
             _ = hook2.Received(1).AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
             _ = hook1.Received(1).AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
-            _ = hook2.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), null);
-            _ = hook1.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), null);
+            _ = hook2.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
+            _ = hook1.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
         }
 
         [Fact]
@@ -458,7 +460,7 @@ public async Task Hook_Hints_May_Be_Optional()
             hook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>())
                 .Returns(new ValueTask());
 
-            hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>())
+            hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>())
                 .Returns(new ValueTask());
 
             await Api.Instance.SetProviderAsync(featureProvider);
@@ -471,7 +473,7 @@ public async Task Hook_Hints_May_Be_Optional()
                 hook.Received().BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>());
                 featureProvider.Received().ResolveBooleanValueAsync("test", false, Arg.Any<EvaluationContext>());
                 hook.Received().AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>());
-                hook.Received().FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>());
+                hook.Received().FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>());
             });
         }
 
@@ -489,7 +491,7 @@ public async Task When_Error_Occurs_In_Before_Hook_Should_Return_Default_Value()
             // Sequence
             hook.BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>()).Throws(exceptionToThrow);
             hook.ErrorAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Exception>(), null).Returns(new ValueTask());
-            hook.FinallyAsync(Arg.Any<HookContext<bool>>(), null).Returns(new ValueTask());
+            hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null).Returns(new ValueTask());
 
             var client = Api.Instance.GetClient();
             client.AddHooks(hook);
@@ -500,13 +502,13 @@ public async Task When_Error_Occurs_In_Before_Hook_Should_Return_Default_Value()
             {
                 hook.BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>());
                 hook.ErrorAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Exception>(), null);
-                hook.FinallyAsync(Arg.Any<HookContext<bool>>(), null);
+                hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
             });
 
             resolvedFlag.Should().BeTrue();
             _ = hook.Received(1).BeforeAsync(Arg.Any<HookContext<bool>>(), null);
             _ = hook.Received(1).ErrorAsync(Arg.Any<HookContext<bool>>(), exceptionToThrow, null);
-            _ = hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), null);
+            _ = hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), null);
         }
 
         [Fact]
@@ -536,7 +538,7 @@ public async Task When_Error_Occurs_In_After_Hook_Should_Invoke_Error_Hook()
             hook.ErrorAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Exception>(), Arg.Any<ImmutableDictionary<string, object>>())
                 .Returns(new ValueTask());
 
-            hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>())
+            hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>())
                 .Returns(new ValueTask());
 
             await Api.Instance.SetProviderAsync(featureProvider);
@@ -550,7 +552,7 @@ public async Task When_Error_Occurs_In_After_Hook_Should_Invoke_Error_Hook()
             {
                 hook.Received(1).BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>());
                 hook.Received(1).AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>());
-                hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>());
+                hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>());
             });
 
             await featureProvider.DidNotReceive().ResolveBooleanValueAsync("test", false, Arg.Any<EvaluationContext>());
@@ -569,7 +571,7 @@ public async Task Successful_Resolution_Should_Pass_Cancellation_Token()
             hook.BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>(), cts.Token).Returns(EvaluationContext.Empty);
             featureProvider.ResolveBooleanValueAsync(Arg.Any<string>(), Arg.Any<bool>(), Arg.Any<EvaluationContext>(), cts.Token).Returns(new ResolutionDetails<bool>("test", false));
             _ = hook.AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>(), cts.Token);
-            _ = hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>(), cts.Token);
+            _ = hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>(), cts.Token);
 
             await Api.Instance.SetProviderAsync(featureProvider);
             var client = Api.Instance.GetClient();
@@ -579,7 +581,7 @@ public async Task Successful_Resolution_Should_Pass_Cancellation_Token()
 
             _ = hook.Received(1).BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>(), cts.Token);
             _ = hook.Received(1).AfterAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>(), cts.Token);
-            _ = hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Dictionary<string, object>>(), cts.Token);
+            _ = hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<Dictionary<string, object>>(), cts.Token);
         }
 
         [Fact]
@@ -606,7 +608,7 @@ public async Task Failed_Resolution_Should_Pass_Cancellation_Token()
             hook.ErrorAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Exception>(), Arg.Any<ImmutableDictionary<string, object>>())
                 .Returns(new ValueTask());
 
-            hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>())
+            hook.FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>())
                 .Returns(new ValueTask());
 
             await Api.Instance.SetProviderAsync(featureProvider);
@@ -616,7 +618,7 @@ public async Task Failed_Resolution_Should_Pass_Cancellation_Token()
 
             _ = hook.Received(1).BeforeAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>(), cts.Token);
             _ = hook.Received(1).ErrorAsync(Arg.Any<HookContext<bool>>(), Arg.Any<Exception>(), Arg.Any<ImmutableDictionary<string, object>>(), cts.Token);
-            _ = hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<ImmutableDictionary<string, object>>(), cts.Token);
+            _ = hook.Received(1).FinallyAsync(Arg.Any<HookContext<bool>>(), Arg.Any<FlagEvaluationDetails<bool>>(), Arg.Any<ImmutableDictionary<string, object>>(), cts.Token);
 
             await featureProvider.DidNotReceive().ResolveBooleanValueAsync("test", false, Arg.Any<EvaluationContext>());
         }
diff --git a/test/OpenFeature.Tests/TestImplementations.cs b/test/OpenFeature.Tests/TestImplementations.cs
index aa4dc784..724278e8 100644
--- a/test/OpenFeature.Tests/TestImplementations.cs
+++ b/test/OpenFeature.Tests/TestImplementations.cs
@@ -48,6 +48,7 @@ public override ValueTask ErrorAsync<T>(HookContext<T> context, Exception error,
         }
 
         public override ValueTask FinallyAsync<T>(HookContext<T> context,
+            FlagEvaluationDetails<T> evaluationDetails,
             IReadOnlyDictionary<string, object>? hints = null, CancellationToken cancellationToken = default)
         {
             Interlocked.Increment(ref this._finallyCallCount);