diff --git a/xml/System.Reflection.Metadata/MetadataUpdateHandlerAttribute.xml b/xml/System.Reflection.Metadata/MetadataUpdateHandlerAttribute.xml
index bc0a934528a..9e27664faac 100644
--- a/xml/System.Reflection.Metadata/MetadataUpdateHandlerAttribute.xml
+++ b/xml/System.Reflection.Metadata/MetadataUpdateHandlerAttribute.xml
@@ -20,8 +20,20 @@
     </Attribute>
   </Attributes>
   <Docs>
-    <summary>To be added.</summary>
-    <remarks>To be added.</remarks>
+    <summary>Indicates that a type that should receive notifications of metadata updates.</summary>
+    <remarks>
+      <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The <xref:System.Type> specified by this attribute should implement static methods matching the signature of one or more of the following (visibility of the methods does not matter):
+ - `static void ClearCache(Type[]? updatedTypes)`
+ - `static void UpdateApplication(Type[]? updatedTypes)`
+
+After a metadata update is applied, `ClearCache` is invoked for every handler that specifies one. This gives update handlers an opportunity to clear any caches that are inferred based on the application's metadata. After all `ClearCache` methods have been invoked, `UpdateApplication` is invoked for every handler that specifies one.  This enables applications to refresh the application state, trigger a UI re-render, or other such reactions. When specified, the `updatedTypes` parameter contains the set of types that were affected by the metadata update; if it's `null`, any type may have been updated.
+
+      ]]></format>
+    </remarks>
   </Docs>
   <Members>
     <Member MemberName=".ctor">
@@ -47,8 +59,8 @@
         </Parameter>
       </Parameters>
       <Docs>
-        <param name="handlerType">To be added.</param>
-        <summary>To be added.</summary>
+        <param name="handlerType">A type that handles metadata updates and that should be notified when any occur.</param>
+        <summary>Initializes the attribute.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -74,7 +86,7 @@
         <ReturnType>System.Type</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Gets the type that handles metadata updates and that should be notified when any occur.</summary>
         <value>To be added.</value>
         <remarks>To be added.</remarks>
       </Docs>
diff --git a/xml/System.Reflection.Metadata/MetadataUpdater.xml b/xml/System.Reflection.Metadata/MetadataUpdater.xml
index 0a83755e1b8..73547ecd942 100644
--- a/xml/System.Reflection.Metadata/MetadataUpdater.xml
+++ b/xml/System.Reflection.Metadata/MetadataUpdater.xml
@@ -40,12 +40,24 @@
         <Parameter Name="pdbDelta" Type="System.ReadOnlySpan&lt;System.Byte&gt;" />
       </Parameters>
       <Docs>
-        <param name="assembly">To be added.</param>
-        <param name="metadataDelta">To be added.</param>
-        <param name="ilDelta">To be added.</param>
-        <param name="pdbDelta">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="assembly">The assembly to update.</param>
+        <param name="metadataDelta">The metadata changes to be applied.</param>
+        <param name="ilDelta">The IL changes to be applied.</param>
+        <param name="pdbDelta">The PDB changes to be applied.</param>
+        <summary>Updates the specified assembly using the provided metadata, IL, and PDB deltas.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Currently executing methods will continue to use the existing IL. New executions of modified methods will use the new IL. Different runtimes may have different limitations on what kinds of changes are supported, and runtimes make no guarantees as to the state of the assembly and process if the delta includes unsupported changes.
+
+          ]]></format>
+        </remarks>
+        <exception cref="T:System.ArgumentException">The assembly argument is not a runtime assembly.</exception>
+        <exception cref="T:System.ArgumentNullException">The assembly argument is <see langword="null" />.</exception>
+        <exception cref="T:System.InvalidOperationException">The assembly is not editable.</exception>
+        <exception cref="T:System.NotSupportedException">The update could not be applied.</exception>
       </Docs>
     </Member>
     <Member MemberName="IsSupported">
@@ -64,8 +76,8 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a value that indicates whether the assembly update is enabled and available.</summary>
+        <value><see langword="true" /> if the assembly update is enabled and available; otherwise, <see langword="false" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
diff --git a/xml/System.Reflection/NullabilityInfo.xml b/xml/System.Reflection/NullabilityInfo.xml
index 280366e2ebb..8558d480923 100644
--- a/xml/System.Reflection/NullabilityInfo.xml
+++ b/xml/System.Reflection/NullabilityInfo.xml
@@ -14,7 +14,7 @@
   </Base>
   <Interfaces />
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Represents nullability information.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -34,8 +34,8 @@
         <ReturnType>System.Reflection.NullabilityInfo</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the nullability information for the element type of the array.</summary>
+        <value>If the member type is an array, the <see cref="T:System.Reflection.NullabilityInfo" /> of the elements of the array; otherwise, <see langword="null" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -55,8 +55,8 @@
         <ReturnType>System.Reflection.NullabilityInfo[]</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the nullability information for each type parameter.</summary>
+        <value>If the member type is a generic type, the nullability information for each type parameter.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -76,7 +76,7 @@
         <ReturnType>System.Reflection.NullabilityState</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Gets the nullability read state of the member.</summary>
         <value>To be added.</value>
         <remarks>To be added.</remarks>
       </Docs>
@@ -97,7 +97,7 @@
         <ReturnType>System.Type</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Gets the type of the member or generic parameter to which this instance belongs.</summary>
         <value>To be added.</value>
         <remarks>To be added.</remarks>
       </Docs>
@@ -118,7 +118,7 @@
         <ReturnType>System.Reflection.NullabilityState</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Gets the nullability write state of the member.</summary>
         <value>To be added.</value>
         <remarks>To be added.</remarks>
       </Docs>
diff --git a/xml/System.Reflection/NullabilityInfoContext.xml b/xml/System.Reflection/NullabilityInfoContext.xml
index bdbefb1fb1d..b885f993b95 100644
--- a/xml/System.Reflection/NullabilityInfoContext.xml
+++ b/xml/System.Reflection/NullabilityInfoContext.xml
@@ -14,7 +14,7 @@
   </Base>
   <Interfaces />
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Provides APIs for populating nullability information and context from reflection members: <see cref="T:System.Reflection.ParameterInfo" />, <see cref="T:System.Reflection.FieldInfo" />, <see cref="T:System.Reflection.PropertyInfo" />, and <see cref="T:System.Reflection.EventInfo" />.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -31,7 +31,7 @@
       </AssemblyInfo>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Initializes a new instance of the <see cref="T:System.Reflection.NullabilityInfoContext"/> class.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -54,10 +54,12 @@
         <Parameter Name="eventInfo" Type="System.Reflection.EventInfo" />
       </Parameters>
       <Docs>
-        <param name="eventInfo">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="eventInfo">The event for which to populate nullability information.</param>
+        <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.EventInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown"/> state.</summary>
+        <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentNullException">
+          <paramref name="eventInfo"/> is <see langword="null"/>.</exception>
       </Docs>
     </Member>
     <Member MemberName="Create">
@@ -79,10 +81,12 @@
         <Parameter Name="fieldInfo" Type="System.Reflection.FieldInfo" />
       </Parameters>
       <Docs>
-        <param name="fieldInfo">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="fieldInfo">The field for which to populate the nullability information.</param>
+        <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.FieldInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown"/> state.</summary>
+        <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentNullException">
+          <paramref name="fieldInfo"/> is <see langword="null"/>.</exception>
       </Docs>
     </Member>
     <Member MemberName="Create">
@@ -104,10 +108,12 @@
         <Parameter Name="parameterInfo" Type="System.Reflection.ParameterInfo" />
       </Parameters>
       <Docs>
-        <param name="parameterInfo">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="parameterInfo">The parameter for which to populate the nullability information.</param>
+        <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.ParameterInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown"/> state.</summary>
+        <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentNullException">
+          <paramref name="parameterInfo"/> is <see langword="null"/>.</exception>
       </Docs>
     </Member>
     <Member MemberName="Create">
@@ -129,10 +135,12 @@
         <Parameter Name="propertyInfo" Type="System.Reflection.PropertyInfo" />
       </Parameters>
       <Docs>
-        <param name="propertyInfo">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="propertyInfo">The property for which to populate the nullability information.</param>
+        <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.PropertyInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown"/> state.</summary>
+        <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentNullException">
+          <paramref name="propertyInfo"/> is <see langword="null"/>.</exception>
       </Docs>
     </Member>
   </Members>
diff --git a/xml/System.Reflection/NullabilityState.xml b/xml/System.Reflection/NullabilityState.xml
index 7da1d89c239..83a1e9bcde1 100644
--- a/xml/System.Reflection/NullabilityState.xml
+++ b/xml/System.Reflection/NullabilityState.xml
@@ -13,7 +13,7 @@
     <BaseTypeName>System.Enum</BaseTypeName>
   </Base>
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Describes nullability states.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -34,7 +34,7 @@
       </ReturnValue>
       <MemberValue>1</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Non-nullable value or reference type.</summary>
       </Docs>
     </Member>
     <Member MemberName="Nullable">
@@ -54,7 +54,7 @@
       </ReturnValue>
       <MemberValue>2</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Nullable value or reference type.</summary>
       </Docs>
     </Member>
     <Member MemberName="Unknown">
@@ -74,7 +74,7 @@
       </ReturnValue>
       <MemberValue>0</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Nullability context not enabled (oblivious).</summary>
       </Docs>
     </Member>
   </Members>