diff --git a/bin/console b/bin/console
index eef3d6c0..86dcbbcc 100755
--- a/bin/console
+++ b/bin/console
@@ -2,7 +2,7 @@
 # frozen_string_literal: true
 
 require "bundler/setup"
-require "openfeature/sdk"
+require "open_feature/sdk"
 
 # You can add fixtures and/or initialization code here to make experimenting
 # with your gem easier. You can also use a different console, if you like.
diff --git a/lib/open_feature/sdk/api.rb b/lib/open_feature/sdk/api.rb
index 3fb2a947..da71f41b 100644
--- a/lib/open_feature/sdk/api.rb
+++ b/lib/open_feature/sdk/api.rb
@@ -4,9 +4,10 @@
 require "singleton"
 
 require_relative "configuration"
+require_relative "evaluation_details"
 require_relative "client"
 require_relative "metadata"
-require_relative "provider/no_op_provider"
+require_relative "provider"
 
 module OpenFeature
   module SDK
@@ -29,9 +30,7 @@ class API
       include Singleton
       extend Forwardable
 
-      def_delegator :@configuration, :provider
-      def_delegator :@configuration, :hooks
-      def_delegator :@configuration, :context
+      def_delegators :configuration, :provider, :hooks, :context
 
       def configuration
         @configuration ||= Configuration.new
diff --git a/lib/open_feature/sdk/client.rb b/lib/open_feature/sdk/client.rb
index b05de912..418bc2e5 100644
--- a/lib/open_feature/sdk/client.rb
+++ b/lib/open_feature/sdk/client.rb
@@ -26,8 +26,9 @@ def initialize(provider:, client_options: nil, context: nil)
             #   result = @provider.fetch_boolean_value(flag_key: flag_key, default_value: default_value, evaluation_context: evaluation_context)
             # end
             def fetch_#{result_type}_#{suffix}(flag_key:, default_value:, evaluation_context: nil)
-              result = @provider.fetch_#{result_type}_value(flag_key: flag_key, default_value: default_value, evaluation_context: evaluation_context)
-              #{"result.value" if suffix == :value}
+              resolution_details = @provider.fetch_#{result_type}_value(flag_key:, default_value:, evaluation_context:)
+              evaluation_details = EvaluationDetails.new(flag_key:, resolution_details:)
+              #{"evaluation_details.value" if suffix == :value}
             end
           RUBY
         end
diff --git a/lib/open_feature/sdk/evaluation_details.rb b/lib/open_feature/sdk/evaluation_details.rb
new file mode 100644
index 00000000..4faccd28
--- /dev/null
+++ b/lib/open_feature/sdk/evaluation_details.rb
@@ -0,0 +1,9 @@
+module OpenFeature
+  module SDK
+    EvaluationDetails = Struct.new(:flag_key, :resolution_details, keyword_init: true) do
+      extend Forwardable
+
+      def_delegators :resolution_details, :value, :reason, :variant, :error_code, :error_message, :flag_metadata
+    end
+  end
+end
diff --git a/lib/open_feature/sdk/provider.rb b/lib/open_feature/sdk/provider.rb
new file mode 100644
index 00000000..8533cd92
--- /dev/null
+++ b/lib/open_feature/sdk/provider.rb
@@ -0,0 +1,11 @@
+require_relative "provider/error_code"
+require_relative "provider/reason"
+require_relative "provider/resolution_details"
+require_relative "provider/no_op_provider"
+
+module OpenFeature
+  module SDK
+    module Provider
+    end
+  end
+end
diff --git a/lib/open_feature/sdk/provider/error_code.rb b/lib/open_feature/sdk/provider/error_code.rb
new file mode 100644
index 00000000..6e10dbda
--- /dev/null
+++ b/lib/open_feature/sdk/provider/error_code.rb
@@ -0,0 +1,15 @@
+module OpenFeature
+  module SDK
+    module Provider
+      module ErrorCode
+        PROVIDER_NOT_READY = "Provider Not Ready"
+        FLAG_NOT_FOUND = "Flag Not Found"
+        PARSE_ERROR = "Parse Error"
+        TYPE_MISMATCH = "Type Mismatch"
+        TARGETING_KEY_MISSING = "Targeting Key Missing"
+        INVALID_CONTEXT = "Invalid Context"
+        GENERAL = "General"
+      end
+    end
+  end
+end
diff --git a/lib/open_feature/sdk/provider/no_op_provider.rb b/lib/open_feature/sdk/provider/no_op_provider.rb
index ef2a7507..c80118be 100644
--- a/lib/open_feature/sdk/provider/no_op_provider.rb
+++ b/lib/open_feature/sdk/provider/no_op_provider.rb
@@ -30,8 +30,6 @@ class NoOpProvider
 
         attr_reader :metadata
 
-        ResolutionDetails = Struct.new(:value, :reason, :variant, :error_code, :error_message)
-
         def initialize
           @metadata = Metadata.new(name: NAME).freeze
         end
diff --git a/lib/open_feature/sdk/provider/reason.rb b/lib/open_feature/sdk/provider/reason.rb
new file mode 100644
index 00000000..15e459a9
--- /dev/null
+++ b/lib/open_feature/sdk/provider/reason.rb
@@ -0,0 +1,17 @@
+module OpenFeature
+  module SDK
+    module Provider
+      module Reason
+        STATIC = "Static"
+        DEFAULT = "Default"
+        TARGETING_MATCH = "Targeting Match"
+        SPLIT = "Split"
+        CACHED = "Cached"
+        DISABLED = "Disabled"
+        UNKNOWN = "Unknown"
+        STALE = "Stale"
+        ERROR = "Error"
+      end
+    end
+  end
+end
diff --git a/lib/open_feature/sdk/provider/resolution_details.rb b/lib/open_feature/sdk/provider/resolution_details.rb
new file mode 100644
index 00000000..c7675fce
--- /dev/null
+++ b/lib/open_feature/sdk/provider/resolution_details.rb
@@ -0,0 +1,7 @@
+module OpenFeature
+  module SDK
+    module Provider
+      ResolutionDetails = Struct.new(:value, :reason, :variant, :error_code, :error_message, :flag_metadata, keyword_init: true)
+    end
+  end
+end
diff --git a/spec/open_feature/sdk/client_spec.rb b/spec/open_feature/sdk/client_spec.rb
index d98b8aef..38b6d8ee 100644
--- a/spec/open_feature/sdk/client_spec.rb
+++ b/spec/open_feature/sdk/client_spec.rb
@@ -103,7 +103,7 @@
           end
 
           it do
-            expect(client.fetch_boolean_details(flag_key: flag_key, default_value: false)).is_a?(OpenFeature::SDK::Provider::NoOpProvider::ResolutionDetails)
+            expect(client.fetch_boolean_details(flag_key: flag_key, default_value: false)).is_a?(OpenFeature::SDK::Provider::ResolutionDetails)
           end
         end
 
@@ -136,8 +136,8 @@
           end
 
           it do
-            expect(client.fetch_number_details(flag_key: flag_key, default_value: 1.2)).is_a?(OpenFeature::SDK::Provider::NoOpProvider::ResolutionDetails)
-            expect(client.fetch_number_details(flag_key: flag_key, default_value: 1)).is_a?(OpenFeature::SDK::Provider::NoOpProvider::ResolutionDetails)
+            expect(client.fetch_number_details(flag_key: flag_key, default_value: 1.2)).is_a?(OpenFeature::SDK::Provider::ResolutionDetails)
+            expect(client.fetch_number_details(flag_key: flag_key, default_value: 1)).is_a?(OpenFeature::SDK::Provider::ResolutionDetails)
           end
         end
 
@@ -166,7 +166,7 @@
           end
 
           it do
-            expect(client.fetch_string_details(flag_key: flag_key, default_value: "some-string")).is_a?(OpenFeature::SDK::Provider::NoOpProvider::ResolutionDetails)
+            expect(client.fetch_string_details(flag_key: flag_key, default_value: "some-string")).is_a?(OpenFeature::SDK::Provider::ResolutionDetails)
           end
         end
 
@@ -195,7 +195,7 @@
 
           it do
             expect(client.fetch_object_details(flag_key: flag_key,
-              default_value: {name: "some-name"})).is_a?(OpenFeature::SDK::Provider::NoOpProvider::ResolutionDetails)
+              default_value: {name: "some-name"})).is_a?(OpenFeature::SDK::Provider::ResolutionDetails)
           end
         end