diff --git a/components/optimization_guide/core/model_execution/feature_keys.h b/components/optimization_guide/core/model_execution/feature_keys.h
index 336fad3d69423..c6e8610c02b04 100644
--- a/components/optimization_guide/core/model_execution/feature_keys.h
+++ b/components/optimization_guide/core/model_execution/feature_keys.h
@@ -46,6 +46,8 @@ enum class ModelBasedCapabilityKey {
       proto::ModelExecutionFeature::MODEL_EXECUTION_FEATURE_PERMISSIONS_AI,
   kWritingAssistanceApi = proto::ModelExecutionFeature::
       MODEL_EXECUTION_FEATURE_WRITING_ASSISTANCE_API,
+  kEnhancedCalendar =
+      proto::ModelExecutionFeature::MODEL_EXECUTION_FEATURE_ENHANCED_CALENDAR,
 };
 
 inline std::ostream& operator<<(std::ostream& out,
@@ -85,11 +87,13 @@ inline std::ostream& operator<<(std::ostream& out,
       return out << "PermissionsAi";
     case ModelBasedCapabilityKey::kWritingAssistanceApi:
       return out << "WritingAssistanceApi";
+    case ModelBasedCapabilityKey::kEnhancedCalendar:
+      return out << "EnhancedCalendar";
   }
   return out;
 }
 
-inline constexpr std::array<ModelBasedCapabilityKey, 17>
+inline constexpr std::array<ModelBasedCapabilityKey, 18>
     kAllModelBasedCapabilityKeys = {
         ModelBasedCapabilityKey::kCompose,
         ModelBasedCapabilityKey::kTabOrganization,
@@ -108,6 +112,7 @@ inline constexpr std::array<ModelBasedCapabilityKey, 17>
         ModelBasedCapabilityKey::kScamDetection,
         ModelBasedCapabilityKey::kPermissionsAi,
         ModelBasedCapabilityKey::kWritingAssistanceApi,
+        ModelBasedCapabilityKey::kEnhancedCalendar,
 };
 
 // A "real" feature implemented by a model-based capability.
@@ -192,6 +197,9 @@ inline ModelBasedCapabilityKey ToModelBasedCapabilityKey(
     case proto::ModelExecutionFeature::
         MODEL_EXECUTION_FEATURE_WRITING_ASSISTANCE_API:
       return ModelBasedCapabilityKey::kWritingAssistanceApi;
+    case proto::ModelExecutionFeature::
+        MODEL_EXECUTION_FEATURE_ENHANCED_CALENDAR:
+      return ModelBasedCapabilityKey::kEnhancedCalendar;
     case proto::ModelExecutionFeature::MODEL_EXECUTION_FEATURE_UNSPECIFIED:
       NOTREACHED() << "Invalid feature";
   }
@@ -246,6 +254,9 @@ inline proto::ModelExecutionFeature ToModelExecutionFeatureProto(
     case ModelBasedCapabilityKey::kWritingAssistanceApi:
       return proto::ModelExecutionFeature::
           MODEL_EXECUTION_FEATURE_WRITING_ASSISTANCE_API;
+    case ModelBasedCapabilityKey::kEnhancedCalendar:
+      return proto::ModelExecutionFeature::
+          MODEL_EXECUTION_FEATURE_ENHANCED_CALENDAR;
   }
 }
 
diff --git a/components/optimization_guide/core/model_execution/model_execution_features.cc b/components/optimization_guide/core/model_execution/model_execution_features.cc
index feae91a20937c..717de0829ee3b 100644
--- a/components/optimization_guide/core/model_execution/model_execution_features.cc
+++ b/components/optimization_guide/core/model_execution/model_execution_features.cc
@@ -174,6 +174,7 @@ std::optional<proto::OptimizationTarget> GetOptimizationTargetForCapability(
     case ModelBasedCapabilityKey::kTextSafety:
     case ModelBasedCapabilityKey::kBlingPrototyping:
     case ModelBasedCapabilityKey::kPasswordChangeSubmission:
+    case ModelBasedCapabilityKey::kEnhancedCalendar:
       return std::nullopt;
   }
 }
diff --git a/components/optimization_guide/core/model_execution/model_execution_fetcher.cc b/components/optimization_guide/core/model_execution/model_execution_fetcher.cc
index f12f4918584ba..09a7477ded7c7 100644
--- a/components/optimization_guide/core/model_execution/model_execution_fetcher.cc
+++ b/components/optimization_guide/core/model_execution/model_execution_fetcher.cc
@@ -222,6 +222,9 @@ net::NetworkTrafficAnnotationTag GetNetworkTrafficAnnotation(
     case ModelBasedCapabilityKey::kFormsClassifications:
       // TODO(crbug.com/389631477) - Add traffic annotation.
       return MISSING_TRAFFIC_ANNOTATION;
+    case ModelBasedCapabilityKey::kEnhancedCalendar:
+      // TODO(crbug.com/398296762): Add network traffic annotation.
+      return MISSING_TRAFFIC_ANNOTATION;
     case ModelBasedCapabilityKey::kHistorySearch:
     case ModelBasedCapabilityKey::kHistoryQueryIntent:
     case ModelBasedCapabilityKey::kPromptApi:
diff --git a/components/optimization_guide/core/optimization_guide_util.cc b/components/optimization_guide/core/optimization_guide_util.cc
index 57dc841413e36..0be83717a7da7 100644
--- a/components/optimization_guide/core/optimization_guide_util.cc
+++ b/components/optimization_guide/core/optimization_guide_util.cc
@@ -108,6 +108,9 @@ std::string_view GetStringNameForModelExecutionFeature(
     case proto::ModelExecutionFeature::
         MODEL_EXECUTION_FEATURE_WRITING_ASSISTANCE_API:
       return "WritingAssistanceApi";
+    case proto::ModelExecutionFeature::
+        MODEL_EXECUTION_FEATURE_ENHANCED_CALENDAR:
+      return "EnhancedCalendar";
     case proto::ModelExecutionFeature::MODEL_EXECUTION_FEATURE_UNSPECIFIED:
       return "Unknown";
       // Must be in sync with the ModelExecutionFeature variant in
diff --git a/components/optimization_guide/proto/BUILD.gn b/components/optimization_guide/proto/BUILD.gn
index fb3f933463554..7ae0a91c5dca5 100644
--- a/components/optimization_guide/proto/BUILD.gn
+++ b/components/optimization_guide/proto/BUILD.gn
@@ -21,6 +21,7 @@ proto_library("optimization_guide_proto") {
     "features/common_quality_data.proto",
     "features/compose.proto",
     "features/default.proto",
+    "features/enhanced_calendar.proto",
     "features/example_for_testing.proto",
     "features/forms_annotations.proto",
     "features/forms_classifications.proto",
diff --git a/components/optimization_guide/proto/model_execution.proto b/components/optimization_guide/proto/model_execution.proto
index c724392687702..61c28ebeb0ec4 100644
--- a/components/optimization_guide/proto/model_execution.proto
+++ b/components/optimization_guide/proto/model_execution.proto
@@ -78,4 +78,5 @@ enum ModelExecutionFeature {
   MODEL_EXECUTION_FEATURE_PERMISSIONS_AI = 17;
   MODEL_EXECUTION_FEATURE_WRITING_ASSISTANCE_API = 18;
   MODEL_EXECUTION_FEATURE_FORMS_CLASSIFICATIONS = 20;
+  MODEL_EXECUTION_FEATURE_ENHANCED_CALENDAR = 23;
 }
diff --git a/tools/metrics/histograms/metadata/optimization/histograms.xml b/tools/metrics/histograms/metadata/optimization/histograms.xml
index df61b5aad7d0b..411dcf29b04a6 100644
--- a/tools/metrics/histograms/metadata/optimization/histograms.xml
+++ b/tools/metrics/histograms/metadata/optimization/histograms.xml
@@ -34,7 +34,9 @@ chromium-metrics-reviews@google.com.
 </variants>
 
 <variants name="ModelExecutionFeature">
+  <variant name="BlingPrototyping" summary="Bling Prototyping"/>
   <variant name="Compose" summary="Compose"/>
+  <variant name="EnhancedCalendar" summary="Enhanced Calendar"/>
   <variant name="FormsAnnotations" summary="Forms Annotations"/>
   <variant name="FormsClassifications" summary="Forms Classifications"/>
   <variant name="FormsPredictions" summary="Forms Predictions"/>