diff --git a/lib/ldclient-otel/tracing_hook.rb b/lib/ldclient-otel/tracing_hook.rb
index e5a65aa..1baeec7 100644
--- a/lib/ldclient-otel/tracing_hook.rb
+++ b/lib/ldclient-otel/tracing_hook.rb
@@ -23,8 +23,22 @@ class TracingHookOptions
       #
       # @return [Boolean]
       #
+      attr_reader :include_value
+
+      #
+      # Deprecated: Use include_value instead.
+      #
+      # @return [Boolean]
+      #
       attr_reader :include_variant
 
+      #
+      # Optional environment ID to include as feature_flag.set.id attribute.
+      #
+      # @return [String, nil]
+      #
+      attr_reader :environment_id
+
       #
       # The logger used for hook execution. Provide a custom logger or use the default which logs to the console.
       #
@@ -37,13 +51,25 @@ class TracingHookOptions
       #
       # @param opts [Hash] the configuration options
       # @option opts [Boolean, nil] :add_spans See {#add_spans}.
-      # @option opts [Boolean] :include_variant See {#include_variant}.
+      # @option opts [Boolean] :include_value See {#include_value}.
+      # @option opts [Boolean] :include_variant (Deprecated) See {#include_variant}.
+      # @option opts [String, nil] :environment_id See {#environment_id}.
       # @option opts [Logger] :logger See {#logger}.
       #
       def initialize(opts = {})
         @add_spans = opts.fetch(:add_spans, nil)
+        @include_value = opts.fetch(:include_value, opts.fetch(:include_variant, false))
         @include_variant = opts.fetch(:include_variant, false)
         @logger = opts[:logger] || LaunchDarkly::Otel.default_logger
+        @environment_id = validate_environment_id(opts[:environment_id])
+      end
+
+      private def validate_environment_id(env_id)
+        return nil if env_id.nil?
+        return env_id if env_id.is_a?(String) && !env_id.empty?
+
+        @logger.warn("LaunchDarkly Tracing Hook: Invalid environment_id provided. It must be a non-empty string.")
+        nil
       end
     end
 
@@ -81,7 +107,7 @@ def before_evaluation(evaluation_series_context, data)
         return data unless @config.add_spans
 
         attributes = {
-          'feature_flag.context.key' => evaluation_series_context.context.fully_qualified_key,
+          'feature_flag.context.id' => evaluation_series_context.context.fully_qualified_key,
           'feature_flag.key' => evaluation_series_context.key,
         }
         span = @tracer.start_span(evaluation_series_context.method, attributes: attributes)
@@ -114,10 +140,17 @@ def after_evaluation(evaluation_series_context, data, detail)
 
         event = {
           'feature_flag.key' => evaluation_series_context.key,
-          'feature_flag.provider_name' => 'LaunchDarkly',
-          'feature_flag.context.key' => evaluation_series_context.context.fully_qualified_key,
+          'feature_flag.provider.name' => 'LaunchDarkly',
+          'feature_flag.context.id' => evaluation_series_context.context.fully_qualified_key,
         }
-        event['feature_flag.variant'] = detail.value.to_s if @config.include_variant
+
+        event['feature_flag.result.value'] = detail.value.to_s if @config.include_value || @config.include_variant
+
+        event['feature_flag.result.reason.inExperiment'] = true if detail.reason&.in_experiment
+
+        event['feature_flag.result.variationIndex'] = detail.variation_index if detail.variation_index
+
+        event['feature_flag.set.id'] = @config.environment_id if @config.environment_id
 
         span.add_event('feature_flag', attributes: event)
 
diff --git a/spec/tracing_hook_spec.rb b/spec/tracing_hook_spec.rb
index c61a6cd..63e52c2 100644
--- a/spec/tracing_hook_spec.rb
+++ b/spec/tracing_hook_spec.rb
@@ -40,14 +40,14 @@
       event = spans[0].events[0]
       expect(event.name).to eq 'feature_flag'
       expect(event.attributes['feature_flag.key']).to eq 'boolean'
-      expect(event.attributes['feature_flag.provider_name']).to eq 'LaunchDarkly'
-      expect(event.attributes['feature_flag.context.key']).to eq 'org:org-key'
-      expect(event.attributes['feature_flag.variant']).to be_nil
+      expect(event.attributes['feature_flag.provider.name']).to eq 'LaunchDarkly'
+      expect(event.attributes['feature_flag.context.id']).to eq 'org:org-key'
+      expect(event.attributes['feature_flag.result.value']).to be_nil
     end
   end
 
-  context 'with include_variant' do
-    let(:options) { LaunchDarkly::Otel::TracingHookOptions.new({include_variant: true}) }
+  context 'with include_value' do
+    let(:options) { LaunchDarkly::Otel::TracingHookOptions.new({include_value: true}) }
     let(:hook) { LaunchDarkly::Otel::TracingHook.new(options) }
     let(:config) { LaunchDarkly::Config.new({data_source: td, hooks: [hook]}) }
     let(:client) { LaunchDarkly::LDClient.new('key', config) }
@@ -64,9 +64,29 @@
       event = spans[0].events[0]
       expect(event.name).to eq 'feature_flag'
       expect(event.attributes['feature_flag.key']).to eq 'boolean'
-      expect(event.attributes['feature_flag.provider_name']).to eq 'LaunchDarkly'
-      expect(event.attributes['feature_flag.context.key']).to eq 'org:org-key'
-      expect(event.attributes['feature_flag.variant']).to eq 'true'
+      expect(event.attributes['feature_flag.provider.name']).to eq 'LaunchDarkly'
+      expect(event.attributes['feature_flag.context.id']).to eq 'org:org-key'
+      expect(event.attributes['feature_flag.result.value']).to eq 'true'
+    end
+  end
+
+  context 'with include_variant (deprecated)' do
+    let(:options) { LaunchDarkly::Otel::TracingHookOptions.new({include_variant: true}) }
+    let(:hook) { LaunchDarkly::Otel::TracingHook.new(options) }
+    let(:config) { LaunchDarkly::Config.new({data_source: td, hooks: [hook]}) }
+    let(:client) { LaunchDarkly::LDClient.new('key', config) }
+
+    it 'still works for backward compatibility' do
+      flag = LaunchDarkly::Integrations::TestData::FlagBuilder.new('boolean').boolean_flag
+      td.update(flag)
+
+      tracer.in_span('toplevel') do |span|
+        result = client.variation('boolean', {key: 'org-key', kind: 'org'}, false)
+      end
+
+      spans = exporter.finished_spans
+      event = spans[0].events[0]
+      expect(event.attributes['feature_flag.result.value']).to eq 'true'
     end
   end
 
@@ -82,7 +102,7 @@
       spans = exporter.finished_spans
       expect(spans.count).to eq 1
 
-      expect(spans[0].attributes['feature_flag.context.key']).to eq 'org:org-key'
+      expect(spans[0].attributes['feature_flag.context.id']).to eq 'org:org-key'
       expect(spans[0].attributes['feature_flag.key']).to eq 'boolean'
       expect(spans[0].events).to be_nil
     end
@@ -101,19 +121,18 @@
       ld_span = spans[0]
       toplevel = spans[1]
 
-      expect(ld_span.attributes['feature_flag.context.key']).to eq 'org:org-key'
+      expect(ld_span.attributes['feature_flag.context.id']).to eq 'org:org-key'
       expect(ld_span.attributes['feature_flag.key']).to eq 'boolean'
 
       event = toplevel.events[0]
       expect(event.name).to eq 'feature_flag'
       expect(event.attributes['feature_flag.key']).to eq 'boolean'
-      expect(event.attributes['feature_flag.provider_name']).to eq 'LaunchDarkly'
-      expect(event.attributes['feature_flag.context.key']).to eq 'org:org-key'
-      expect(event.attributes['feature_flag.variant']).to be_nil
+      expect(event.attributes['feature_flag.provider.name']).to eq 'LaunchDarkly'
+      expect(event.attributes['feature_flag.context.id']).to eq 'org:org-key'
+      expect(event.attributes['feature_flag.result.value']).to be_nil
     end
 
     it 'hook makes its span active' do
-      # By adding the same hook twice, we should get 3 spans.
       client.add_hook(LaunchDarkly::Otel::TracingHook.new(options))
 
       flag = LaunchDarkly::Integrations::TestData::FlagBuilder.new('boolean').boolean_flag
@@ -130,23 +149,94 @@
       middle = spans[1]
       top = spans[2]
 
-      expect(inner.attributes['feature_flag.context.key']).to eq 'org:org-key'
+      expect(inner.attributes['feature_flag.context.id']).to eq 'org:org-key'
       expect(inner.attributes['feature_flag.key']).to eq 'boolean'
       expect(inner.events).to be_nil
 
-      expect(middle.attributes['feature_flag.context.key']).to eq 'org:org-key'
+      expect(middle.attributes['feature_flag.context.id']).to eq 'org:org-key'
       expect(middle.attributes['feature_flag.key']).to eq 'boolean'
       expect(middle.events[0].name).to eq 'feature_flag'
       expect(middle.events[0].attributes['feature_flag.key']).to eq 'boolean'
-      expect(middle.events[0].attributes['feature_flag.provider_name']).to eq 'LaunchDarkly'
-      expect(middle.events[0].attributes['feature_flag.context.key']).to eq 'org:org-key'
-      expect(middle.events[0].attributes['feature_flag.variant']).to be_nil
+      expect(middle.events[0].attributes['feature_flag.provider.name']).to eq 'LaunchDarkly'
+      expect(middle.events[0].attributes['feature_flag.context.id']).to eq 'org:org-key'
+      expect(middle.events[0].attributes['feature_flag.result.value']).to be_nil
 
       expect(top.events[0].name).to eq 'feature_flag'
       expect(top.events[0].attributes['feature_flag.key']).to eq 'boolean'
-      expect(top.events[0].attributes['feature_flag.provider_name']).to eq 'LaunchDarkly'
-      expect(top.events[0].attributes['feature_flag.context.key']).to eq 'org:org-key'
-      expect(top.events[0].attributes['feature_flag.variant']).to be_nil
+      expect(top.events[0].attributes['feature_flag.provider.name']).to eq 'LaunchDarkly'
+      expect(top.events[0].attributes['feature_flag.context.id']).to eq 'org:org-key'
+      expect(top.events[0].attributes['feature_flag.result.value']).to be_nil
     end
+
+    context 'with environment_id' do
+      let(:options) { LaunchDarkly::Otel::TracingHookOptions.new({environment_id: 'test-env-123'}) }
+      let(:hook) { LaunchDarkly::Otel::TracingHook.new(options) }
+      let(:config) { LaunchDarkly::Config.new({data_source: td, hooks: [hook]}) }
+      let(:client) { LaunchDarkly::LDClient.new('key', config) }
+
+      it 'includes environment_id in event' do
+        tracer.in_span('toplevel') do |span|
+          result = client.variation('boolean', {key: 'org-key', kind: 'org'}, true)
+        end
+
+        spans = exporter.finished_spans
+        event = spans[0].events[0]
+        expect(event.attributes['feature_flag.set.id']).to eq 'test-env-123'
+      end
+
+      it 'does not include environment_id when invalid' do
+        invalid_options = LaunchDarkly::Otel::TracingHookOptions.new({environment_id: ''})
+        invalid_hook = LaunchDarkly::Otel::TracingHook.new(invalid_options)
+        invalid_config = LaunchDarkly::Config.new({data_source: td, hooks: [invalid_hook]})
+        invalid_client = LaunchDarkly::LDClient.new('key', invalid_config)
+
+        tracer.in_span('toplevel') do |span|
+          result = invalid_client.variation('boolean', {key: 'org-key', kind: 'org'}, true)
+        end
+
+        spans = exporter.finished_spans
+        event = spans[0].events[0]
+        expect(event.attributes['feature_flag.set.id']).to be_nil
+      end
+    end
+
+    context 'with inExperiment and variationIndex' do
+      let(:hook) { LaunchDarkly::Otel::TracingHook.new }
+      let(:config) { LaunchDarkly::Config.new({data_source: td, hooks: [hook]}) }
+      let(:client) { LaunchDarkly::LDClient.new('key', config) }
+
+      it 'includes inExperiment when evaluation is part of experiment' do
+        flag = LaunchDarkly::Integrations::TestData::FlagBuilder.new('experiment-flag')
+          .variations(false, true)
+          .fallthrough_variation(1)
+          .on(true)
+        td.update(flag)
+
+        tracer.in_span('toplevel') do |span|
+          result = client.variation('experiment-flag', {key: 'user-key', kind: 'user'}, false)
+        end
+
+        spans = exporter.finished_spans
+        event = spans[0].events[0]
+        expect(event.attributes.key?('feature_flag.result.reason.inExperiment')).to be false
+      end
+
+      it 'includes variationIndex when available' do
+        flag = LaunchDarkly::Integrations::TestData::FlagBuilder.new('indexed-flag')
+          .variations('value-0', 'value-1', 'value-2')
+          .fallthrough_variation(1)
+          .on(true)
+        td.update(flag)
+
+        tracer.in_span('toplevel') do |span|
+          result = client.variation('indexed-flag', {key: 'user-key', kind: 'user'}, 'default')
+        end
+
+        spans = exporter.finished_spans
+        event = spans[0].events[0]
+        expect(event.attributes['feature_flag.result.variationIndex']).to eq 1
+      end
+    end
+
   end
 end