Add some reference docs for MVC (#7981)

src/Mvc/Mvc.Abstractions/src/Abstractions/ActionDescriptor.cs

@@ -9,8 +9,14 @@ using Microsoft.AspNetCore.Mvc.Routing;
 
 namespace Microsoft.AspNetCore.Mvc.Abstractions
 {
+    /// <summary>
+    /// Describes a MVC action.
+    /// </summary>
     public class ActionDescriptor
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="ActionDescriptor"/>.
+        /// </summary>
         public ActionDescriptor()
         {
             Id = Guid.NewGuid().ToString();
@@ -29,6 +35,9 @@ namespace Microsoft.AspNetCore.Mvc.Abstractions
         /// </summary>
         public IDictionary<string, string> RouteValues { get; set; }
 
+        /// <summary>
+        /// Gets or sets the <see cref="Routing.AttributeRouteInfo"/>.
+        /// </summary>
         public AttributeRouteInfo AttributeRouteInfo { get; set; }
 
         /// <summary>

src/Mvc/Mvc.Abstractions/src/Abstractions/ActionDescriptorProviderContext.cs

@@ -5,8 +5,15 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Mvc.Abstractions
 {
+    /// <summary>
+    /// A context for <see cref="IActionDescriptorProvider"/>.
+    /// </summary>
     public class ActionDescriptorProviderContext
     {
+        /// <summary>
+        /// Gets the <see cref="IList{T}" /> of <see cref="ActionDescriptor"/> instances of <see cref="IActionDescriptorProvider"/>
+        /// can populate.
+        /// </summary>
         public IList<ActionDescriptor> Results { get; } = new List<ActionDescriptor>();
     }
 }

src/Mvc/Mvc.Abstractions/src/Abstractions/ActionInvokerProviderContext.cs

@@ -5,8 +5,15 @@ using System;
 
 namespace Microsoft.AspNetCore.Mvc.Abstractions
 {
+    /// <summary>
+    /// A context for <see cref="IActionInvokerProvider"/>.
+    /// </summary>
     public class ActionInvokerProviderContext
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="ActionInvokerProviderContext"/>.
+        /// </summary>
+        /// <param name="actionContext">The <see cref="Mvc.ActionContext"/> to invoke.</param>
         public ActionInvokerProviderContext(ActionContext actionContext)
         {
             if (actionContext == null)
@@ -17,8 +24,14 @@ namespace Microsoft.AspNetCore.Mvc.Abstractions
             ActionContext = actionContext;
         }
 
+        /// <summary>
+        /// Gets the <see cref="Mvc.ActionContext"/> to invoke.
+        /// </summary>
         public ActionContext ActionContext { get; }
 
+        /// <summary>
+        /// Gets or sets the <see cref="IActionInvoker"/> that will be used to invoke <see cref="ActionContext" />
+        /// </summary>
         public IActionInvoker Result { get; set; }
     }
 }

src/Mvc/Mvc.Abstractions/src/Abstractions/IActionDescriptorProvider.cs

@@ -3,6 +3,26 @@
 
 namespace Microsoft.AspNetCore.Mvc.Abstractions
 {
+    /// <summary>
+    /// Defines a contract for specifying <see cref="ActionDescriptor"/> instances.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// On application initialization, MVC invokes all registered instances of <see cref="IActionDescriptorProvider"/> to 
+    /// perform <see cref="ActionDescriptor" /> discovery. 
+    /// <see cref="IActionDescriptorProvider"/> instances are invoked in the ascending sort order of <see cref="Order"/>.  
+    /// </para>
+    /// <para>
+    /// Each provider has its <see cref="OnProvidersExecuting"/> method
+    /// called in sequence and given the same instance of <see cref="ActionInvokerProviderContext"/>. Then each
+    /// provider has its <see cref="OnProvidersExecuted"/> method called in the reverse order. Each instance has
+    /// an opportunity to add or modify <see cref="ActionDescriptorProviderContext.Results"/>.
+    /// </para>
+    /// <para>
+    /// As providers are called in a predefined sequence, each provider has a chance to observe and decorate the
+    /// result of the providers that have already run. 
+    /// </para>
+    /// </remarks>
     public interface IActionDescriptorProvider
     {
         /// <summary>
@@ -26,8 +46,19 @@ namespace Microsoft.AspNetCore.Mvc.Abstractions
         /// </remarks>
         int Order { get; }
 
+        /// <summary>
+        /// Called to execute the provider. 
+        /// <see cref="Order"/> for details on the order of execution of <see cref="OnProvidersExecuting(ActionDescriptorProviderContext)"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="ActionDescriptorProviderContext"/>.</param>
         void OnProvidersExecuting(ActionDescriptorProviderContext context);
 
+        /// <summary>
+        /// Called to execute the provider, after the <see cref="OnProvidersExecuting"/> methods of all providers,
+        /// have been called.
+        /// <see cref="Order"/> for details on the order of execution of <see cref="OnProvidersExecuted(ActionDescriptorProviderContext)"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="ActionDescriptorProviderContext"/>.</param>
         void OnProvidersExecuted(ActionDescriptorProviderContext context);
     }
 }

src/Mvc/Mvc.Abstractions/src/Abstractions/ParameterDescriptor.cs

@@ -6,12 +6,24 @@ using Microsoft.AspNetCore.Mvc.ModelBinding;
 
 namespace Microsoft.AspNetCore.Mvc.Abstractions
 {
+    /// <summary>
+    /// Describes a parameter in an action.
+    /// </summary>
     public class ParameterDescriptor
     {
+        /// <summary>
+        /// Gets or sets the parameter name.
+        /// </summary>
         public string Name { get; set; }
 
+        /// <summary>
+        /// Gets or sets the type of the parameter.
+        /// </summary>
         public Type ParameterType { get; set; }
 
+        /// <summary>
+        /// Gets or sets the <see cref="ModelBinding.BindingInfo"/> for the parameter.
+        /// </summary>
         public BindingInfo BindingInfo { get; set; }
     }
 }

src/Mvc/Mvc.Abstractions/src/ActionConstraints/IActionConstraintProvider.cs

@@ -3,6 +3,9 @@
 
 namespace Microsoft.AspNetCore.Mvc.ActionConstraints
 {
+    /// <summary>
+    /// Provider for <see cref="IActionConstraint"/>.
+    /// </summary>
     public interface IActionConstraintProvider
     {
         /// <summary>
@@ -26,8 +29,19 @@ namespace Microsoft.AspNetCore.Mvc.ActionConstraints
         /// </remarks>
         int Order { get; }
 
+        /// <summary>
+        /// Called to execute the provider. 
+        /// <see cref="Order"/> for details on the order of execution of <see cref="OnProvidersExecuting(ActionConstraintProviderContext)"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="ActionConstraintProviderContext"/>.</param>
         void OnProvidersExecuting(ActionConstraintProviderContext context);
 
+        /// <summary>
+        /// Called to execute the provider, after the <see cref="OnProvidersExecuting"/> methods of all providers,
+        /// have been called.
+        /// <see cref="Order"/> for details on the order of execution of <see cref="OnProvidersExecuted(ActionConstraintProviderContext)"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="ActionConstraintProviderContext"/>.</param>
         void OnProvidersExecuted(ActionConstraintProviderContext context);
     }
 }

src/Mvc/Mvc.Abstractions/src/ApiExplorer/IApiDescriptionProvider.cs

@@ -1,8 +1,29 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using Microsoft.AspNetCore.Mvc.Abstractions;
+
 namespace Microsoft.AspNetCore.Mvc.ApiExplorer
 {
+    /// <summary>
+    /// Defines a contract for specifying <see cref="ApiDescription"/> instances.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// On the first query for <see cref="ActionDescriptor"/>, MVC invokes all registered instances of <see cref="IApiDescriptionProvider"/>
+    /// in the ascending sort order of <see cref="Order"/>. 
+    /// </para>
+    /// <para>
+    /// Each provider has its <see cref="OnProvidersExecuting"/> method
+    /// called in sequence and given the same instance of <see cref="ApiDescriptionProviderContext"/>. Then each
+    /// provider has its <see cref="OnProvidersExecuted"/> method called in the reverse order. Each instance has
+    /// an opportunity to add or modify <see cref="ApiDescriptionProviderContext.Results"/>.
+    /// </para>
+    /// <para>
+    /// As providers are called in a predefined sequence, each provider has a chance to observe and decorate the
+    /// result of the providers that have already run. 
+    /// </para>
+    /// </remarks>
     public interface IApiDescriptionProvider
     {
         /// <summary>

src/Mvc/Mvc.Abstractions/src/Formatters/InputFormatterException.cs

@@ -10,15 +10,28 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
     /// </summary>
     public class InputFormatterException : Exception
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="InputFormatterException"/>.
+        /// </summary>
         public InputFormatterException()
         {
         }
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="InputFormatterException"/> with the specified <paramref name="message"/>.
+        /// </summary>
+        /// <param name="message">The exception message.</param>
         public InputFormatterException(string message)
             : base(message)
         {
         }
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="InputFormatterException"/> with the specified <paramref name="message"/> and
+        /// inner exception that is the cause of this exception.
+        /// </summary>
+        /// <param name="message">The exception message.</param>
+        /// <param name="innerException">The exception that is the cause of the current exception.</param>
         public InputFormatterException(string message, Exception innerException)
             : base(message, innerException)
         {

src/Mvc/Mvc.Abstractions/src/Microsoft.AspNetCore.Mvc.Abstractions.csproj

@@ -6,7 +6,6 @@ Commonly used types:
 Microsoft.AspNetCore.Mvc.IActionResult</Description>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;aspnetcoremvc</PackageTags>
   </PropertyGroup>

src/Mvc/Mvc.Abstractions/src/ModelBinding/IModelMetadataProvider.cs

@@ -6,10 +6,26 @@ using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding
 {
+    /// <summary>
+    /// A provider that can supply instances of <see cref="ModelMetadata"/>.
+    /// </summary>
+    /// <remarks>
+    /// While not obsolete, implementing or using <see cref="ModelMetadataProvider" /> is preferred over <see cref="IModelMetadataProvider"/>.
+    /// </remarks>
     public interface IModelMetadataProvider
     {
+        /// <summary>
+        /// Supplies metadata describing a <see cref="Type"/>.
+        /// </summary>
+        /// <param name="modelType">The <see cref="Type"/>.</param>
+        /// <returns>A <see cref="ModelMetadata"/> instance describing the <see cref="Type"/>.</returns>
         ModelMetadata GetMetadataForType(Type modelType);
 
+        /// <summary>
+        /// Supplies metadata describing the properties of a <see cref="Type"/>.
+        /// </summary>
+        /// <param name="modelType">The <see cref="Type"/>.</param>
+        /// <returns>A set of <see cref="ModelMetadata"/> instances describing properties of the <see cref="Type"/>.</returns>
         IEnumerable<ModelMetadata> GetMetadataForProperties(Type modelType);
     }
 }

src/Mvc/Mvc.Abstractions/src/ModelBinding/ModelError.cs

@@ -5,35 +5,49 @@ using System;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding
 {
+    /// <summary>
+    /// An error that occured during model binding and validation.
+    /// </summary>
     public class ModelError
     {
+        /// <summary>
+        /// Intiializes a new instance of <see cref="ModelError"/> with the specified <paramref name="exception"/>.
+        /// </summary>
+        /// <param name="exception">The <see cref="System.Exception"/>.</param>
         public ModelError(Exception exception)
             : this(exception, errorMessage: null)
         {
-            if (exception == null)
-            {
-                throw new ArgumentNullException(nameof(exception));
-            }
         }
 
+        /// <summary>
+        /// Intiializes a new instance of <see cref="ModelError"/> with the specified <paramref name="exception"/>
+        /// and specified <paramref name="errorMessage"/>.
+        /// </summary>
+        /// <param name="exception">The <see cref="System.Exception"/>.</param>
+        /// <param name="errorMessage">The error message.</param>
         public ModelError(Exception exception, string errorMessage)
             : this(errorMessage)
         {
-            if (exception == null)
-            {
-                throw new ArgumentNullException(nameof(exception));
-            }
-
-            Exception = exception;
+            Exception = exception ?? throw new ArgumentNullException(nameof(exception));
         }
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="ModelError"/> with the specified <paramref name="errorMessage"/>.
+        /// </summary>
+        /// <param name="errorMessage">The error message.</param>
         public ModelError(string errorMessage)
         {
             ErrorMessage = errorMessage ?? string.Empty;
         }
 
+        /// <summary>
+        /// Gets the <see cref="System.Exception"/> associated with this <see cref="ModelError"/> instance.
+        /// </summary>
         public Exception Exception { get; }
 
+        /// <summary>
+        /// Gets the error message associated with this <see cref="ModelError"/> instance.
+        /// </summary>
         public string ErrorMessage { get; }
     }
 }

src/Mvc/Mvc.Abstractions/src/ModelBinding/ModelErrorCollection.cs

@@ -6,8 +6,15 @@ using System.Collections.ObjectModel;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding
 {
+    /// <summary>
+    /// A collection of <see cref="ModelError"/> instances.
+    /// </summary>
     public class ModelErrorCollection : Collection<ModelError>
     {
+        /// <summary>
+        /// Adds the specified <paramref name="exception"/> instance.
+        /// </summary>
+        /// <param name="exception">The <see cref="Exception"/></param>
         public void Add(Exception exception)
         {
             if (exception == null)
@@ -18,6 +25,10 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             Add(new ModelError(exception));
         }
 
+        /// <summary>
+        /// Adds the specified error message.
+        /// </summary>
+        /// <param name="errorMessage">The error message.</param>
         public void Add(string errorMessage)
         {
             if (errorMessage == null)

src/Mvc/Mvc.Abstractions/src/ModelBinding/ModelStateDictionary.cs

@@ -797,6 +797,12 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
         /// <inheritdoc />
         IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
 
+        /// <summary>
+        /// <para>
+        /// This API supports the MVC's infrastructure and is not intended to be used
+        /// directly from your code. This API may change or be removed in future releases.
+        /// </para>
+        /// </summary>
         public static bool StartsWithPrefix(string prefix, string key)
         {
             if (prefix == null)
@@ -840,6 +846,12 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             return false;
         }
 
+        /// <summary>
+        /// Gets a <see cref="PrefixEnumerable"/> that iterates over this instance of <see cref="ModelStateDictionary"/>
+        /// using the specified <paramref name="prefix"/>.
+        /// </summary>
+        /// <param name="prefix">The prefix.</param>
+        /// <returns>The <see cref="PrefixEnumerable"/>.</returns>
         public PrefixEnumerable FindKeysWithPrefix(string prefix)
         {
             if (prefix == null)
@@ -1004,11 +1016,20 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             }
         }
 
+        /// <summary>
+        /// Enumerates over <see cref="ModelStateDictionary"/> to provide entries that start with the
+        /// specified prefix.
+        /// </summary>
         public readonly struct PrefixEnumerable : IEnumerable<KeyValuePair<string, ModelStateEntry>>
         {
             private readonly ModelStateDictionary _dictionary;
             private readonly string _prefix;
 
+            /// <summary>
+            /// Initializes a new instance of <see cref="PrefixEnumerable"/>.
+            /// </summary>
+            /// <param name="dictionary">The <see cref="ModelStateDictionary"/>.</param>
+            /// <param name="prefix">The prefix.</param>
             public PrefixEnumerable(ModelStateDictionary dictionary, string prefix)
             {
                 if (dictionary == null)
@@ -1025,6 +1046,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 _prefix = prefix;
             }
 
+            /// <inheritdoc />
             public Enumerator GetEnumerator() => new Enumerator(_dictionary, _prefix);
 
             IEnumerator<KeyValuePair<string, ModelStateEntry>>
@@ -1033,6 +1055,9 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
         }
 
+        /// <summary>
+        /// An <see cref="IEnumerator{T}"/> for <see cref="PrefixEnumerable"/>.
+        /// </summary>
         public struct Enumerator : IEnumerator<KeyValuePair<string, ModelStateEntry>>
         {
             private readonly ModelStateNode _rootNode;
@@ -1041,6 +1066,11 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             private int _index;
             private bool _visitedRoot;
 
+            /// <summary>
+            /// Intializes a new instance of <see cref="Enumerator"/>.
+            /// </summary>
+            /// <param name="dictionary">The <see cref="ModelStateDictionary"/>.</param>
+            /// <param name="prefix">The prefix.</param>
             public Enumerator(ModelStateDictionary dictionary, string prefix)
             {
                 if (dictionary == null)
@@ -1059,16 +1089,19 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 _nodes = null;
                 _visitedRoot = false;
             }
-
+            
+            /// <inheritdoc />
             public KeyValuePair<string, ModelStateEntry> Current =>
                 new KeyValuePair<string, ModelStateEntry>(_modelStateNode.Key, _modelStateNode);
 
             object IEnumerator.Current => Current;
 
+            /// <inheritdoc />
             public void Dispose()
             {
             }
 
+            /// <inheritdoc />
             public bool MoveNext()
             {
                 if (_rootNode == null)
@@ -1128,6 +1161,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 return false;
             }
 
+            /// <inheritdoc />
             public void Reset()
             {
                 _index = -1;
@@ -1137,15 +1171,23 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             }
         }
 
+        /// <summary>
+        /// A <see cref="IEnumerable{T}"/> for keys in <see cref="ModelStateDictionary"/>.
+        /// </summary>
         public readonly struct KeyEnumerable : IEnumerable<string>
         {
             private readonly ModelStateDictionary _dictionary;
 
+            /// <summary>
+            /// Initializes a new instance of <see cref="KeyEnumerable"/>.
+            /// </summary>
+            /// <param name="dictionary">The <see cref="ModelStateDictionary"/>.</param>
             public KeyEnumerable(ModelStateDictionary dictionary)
             {
                 _dictionary = dictionary;
             }
 
+            /// <inheritdoc />
             public KeyEnumerator GetEnumerator() => new KeyEnumerator(_dictionary, prefix: string.Empty);
 
             IEnumerator<string> IEnumerable<string>.GetEnumerator() => GetEnumerator();
@@ -1153,22 +1195,33 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
         }
 
+        /// <summary>
+        /// An <see cref="IEnumerator{T}"/> for keys in <see cref="ModelStateDictionary"/>.
+        /// </summary>
         public struct KeyEnumerator : IEnumerator<string>
         {
             private Enumerator _prefixEnumerator;
 
+            /// <summary>
+            /// Initializes a new instance of <see cref="KeyEnumerable"/>.
+            /// </summary>
+            /// <param name="dictionary">The <see cref="ModelStateDictionary"/>.</param>
+            /// <param name="prefix">The prefix.</param>
             public KeyEnumerator(ModelStateDictionary dictionary, string prefix)
             {
                 _prefixEnumerator = new Enumerator(dictionary, prefix);
                 Current = null;
             }
 
+            /// <inheritdoc />
             public string Current { get; private set; }
 
             object IEnumerator.Current => Current;
 
+            /// <inheritdoc />
             public void Dispose() => _prefixEnumerator.Dispose();
 
+            /// <inheritdoc />
             public bool MoveNext()
             {
                 var result = _prefixEnumerator.MoveNext();
@@ -1185,6 +1238,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 return result;
             }
 
+            /// <inheritdoc />
             public void Reset()
             {
                 _prefixEnumerator.Reset();
@@ -1192,15 +1246,23 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             }
         }
 
+        /// <summary>
+        /// An <see cref="IEnumerable"/> for <see cref="ModelStateEntry"/>.
+        /// </summary>
         public readonly struct ValueEnumerable : IEnumerable<ModelStateEntry>
         {
             private readonly ModelStateDictionary _dictionary;
 
+            /// <summary>
+            /// Initializes a new instance of <see cref="ValueEnumerable"/>.
+            /// </summary>
+            /// <param name="dictionary">The <see cref="ModelStateDictionary"/>.</param>
             public ValueEnumerable(ModelStateDictionary dictionary)
             {
                 _dictionary = dictionary;
             }
 
+            /// <inheritdoc />
             public ValueEnumerator GetEnumerator() => new ValueEnumerator(_dictionary, prefix: string.Empty);
 
             IEnumerator<ModelStateEntry> IEnumerable<ModelStateEntry>.GetEnumerator() => GetEnumerator();
@@ -1208,22 +1270,33 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
         }
 
+        /// <summary>
+        /// An enumerator for <see cref="ModelStateEntry"/>.
+        /// </summary>
         public struct ValueEnumerator : IEnumerator<ModelStateEntry>
         {
             private Enumerator _prefixEnumerator;
 
+            /// <summary>
+            /// Initializes a new instance of <see cref="ValueEnumerator"/>.
+            /// </summary>
+            /// <param name="dictionary">The <see cref="ModelStateDictionary"/>.</param>
+            /// <param name="prefix">The prefix to enumerate.</param>
             public ValueEnumerator(ModelStateDictionary dictionary, string prefix)
             {
                 _prefixEnumerator = new Enumerator(dictionary, prefix);
                 Current = null;
             }
 
+            /// <inheritdoc />
             public ModelStateEntry Current { get; private set; }
 
             object IEnumerator.Current => Current;
 
+            /// <inheritdoc />
             public void Dispose() => _prefixEnumerator.Dispose();
 
+            /// <inheritdoc />
             public bool MoveNext()
             {
                 var result = _prefixEnumerator.MoveNext();
@@ -1240,6 +1313,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 return result;
             }
 
+            /// <inheritdoc />
             public void Reset()
             {
                 _prefixEnumerator.Reset();

src/Mvc/Mvc.Abstractions/src/ModelBinding/ModelValidationState.cs

@@ -3,11 +3,50 @@
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding
 {
+    /// <summary>
+    /// The validation state of a <see cref="ModelStateEntry"/> instance.
+    /// <para>
+    /// <see cref="ModelValidationState"/> of <see cref="ModelStateDictionary.Root"/> is used to determine the validity
+    /// of <see cref="ModelStateDictionary"/>. <see cref="ModelStateDictionary.IsValid"/> is <see langword="true" />, when
+    /// the aggregate validity (<see cref="ModelStateDictionary.GetFieldValidationState(string)"/>) 
+    /// of the root node is <see cref="Valid"/>.
+    /// </para>
+    /// </summary>
     public enum ModelValidationState
     {
+        /// <summary>
+        /// Validation has not been performed on the <see cref="ModelStateEntry"/>.
+        /// <para>
+        /// For aggregate validity, the validation of a <see cref="ModelStateEntry"/> is <see cref="Unvalidated"/>
+        /// if either the entry or one of thedescendants is <see cref="Unvalidated"/>.
+        /// </para>
+        /// </summary>
         Unvalidated,
+
+        /// <summary>
+        /// Validation was performed on the <see cref="ModelStateEntry"/> and was found to be invalid.
+        /// <para>
+        /// For aggregate validity, the validation of a <see cref="ModelStateEntry"/> is <see cref="Invalid"/>
+        /// if either the entry or one of the descendants is <see cref="Invalid"/> and none are <see cref="Unvalidated"/>.
+        /// </para>
+        /// </summary>
         Invalid,
+
+        /// <summary>
+        /// Validation was performed on the <see cref="ModelStateEntry"/>
+        /// <para>
+        /// For aggregate validity, the validation of a <see cref="ModelStateEntry"/> is <see cref="Valid"/>
+        /// if the validity of the entry and all descendants is either <see cref="Valid"/> or <see cref="Skipped"/>.
+        /// </para>
+        /// </summary>
         Valid,
+
+        /// <summary>
+        /// Validation was skipped for the <see cref="ModelStateEntry"/>.
+        /// <para>
+        /// The aggregate validity of an entry is never <see cref="Skipped"/>.
+        /// </para>
+        /// </summary>
         Skipped
     }
 }

src/Mvc/Mvc.Abstractions/src/ModelBinding/Validation/IClientModelValidator.cs

@@ -3,8 +3,20 @@
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding.Validation
 {
+    /// <summary>
+    /// Specifies the contract for performing validation in the browser.
+    /// <para>
+    /// MVC's validation system invokes <see cref="IClientModelValidator"/> to gather attributes that apply to the
+    /// rendered HTML. The rendered view may have to reference JavaScript libraries, such as jQuery Unobtrusive Validation,
+    /// to provide client validation based on the presence of these attributes.
+    /// </para>
+    /// </summary>
     public interface IClientModelValidator
     {
+        /// <summary>
+        /// Called to add client-side model validation.
+        /// </summary>
+        /// <param name="context">The <see cref="ClientModelValidationContext"/>.</param>
         void AddValidation(ClientModelValidationContext context);
     }
 }

src/Mvc/Mvc.Abstractions/src/ModelBinding/Validation/ModelValidationResult.cs

@@ -3,16 +3,30 @@
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding.Validation
 {
+    /// <summary>
+    /// The result of model validation.
+    /// </summary>
     public class ModelValidationResult
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="ModelValidationResult"/>.
+        /// </summary>
+        /// <param name="memberName">The name of the entry on which validation was performed.</param>
+        /// <param name="message">The validation message.</param>
         public ModelValidationResult(string memberName, string message)
         {
             MemberName = memberName ?? string.Empty;
             Message = message ?? string.Empty;
         }
 
+        /// <summary>
+        /// Gets the name of the entry on which validation was performed.
+        /// </summary>
         public string MemberName { get; }
 
+        /// <summary>
+        /// Gets the validation message.
+        /// </summary>
         public string Message { get; }
     }
 }

src/Mvc/Mvc.Abstractions/test/ModelBinding/ModelStateDictionaryTest.cs

@@ -483,6 +483,52 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             Assert.Equal(ModelValidationState.Valid, validationState);
         }
 
+        [Fact]
+        public void GetFieldValidationState_OfSkippedEntry()
+        {
+            // Arrange
+            var modelState = new ModelStateDictionary();
+            modelState.MarkFieldSkipped("foo");
+
+            // Act
+            var validationState = modelState.GetValidationState("foo");
+            var fieldValidationState = modelState.GetFieldValidationState("foo");
+
+            // Assert
+            Assert.Equal(ModelValidationState.Skipped, validationState);
+            Assert.Equal(ModelValidationState.Valid, fieldValidationState);
+        }
+
+        [Fact]
+        public void GetFieldValidationState_WithSkippedProperty()
+        {
+            // Arrange
+            var modelState = new ModelStateDictionary();
+            modelState.MarkFieldSkipped("foo.bar.prop1");
+            modelState.MarkFieldValid("foo.bar.prop2");
+
+            // Act
+            var validationState = modelState.GetFieldValidationState("foo.bar");
+
+            // Assert
+            Assert.Equal(ModelValidationState.Valid, validationState);
+        }
+
+        [Fact]
+        public void GetFieldValidationState_WithAllSkippedProperties()
+        {
+            // Arrange
+            var modelState = new ModelStateDictionary();
+            modelState.MarkFieldSkipped("foo.bar.prop1");
+            modelState.MarkFieldSkipped("foo.bar.prop2");
+
+            // Act
+            var validationState = modelState.GetFieldValidationState("foo.bar");
+
+            // Assert
+            Assert.Equal(ModelValidationState.Valid, validationState);
+        }
+
         [Fact]
         public void IsValidPropertyReturnsFalse_IfSomeFieldsAreNotValidated()
         {

src/Mvc/Mvc.ApiExplorer/src/DefaultApiDescriptionProvider.cs

@@ -83,6 +83,7 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
             }
         }
 
+        /// <inheritdoc />
         public void OnProvidersExecuted(ApiDescriptionProviderContext context)
         {
         }

src/Mvc/Mvc.ApiExplorer/src/DependencyInjection/MvcApiExplorerMvcCoreBuilderExtensions.cs

@@ -7,8 +7,16 @@ using Microsoft.Extensions.DependencyInjection.Extensions;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
+    /// <summary>
+    /// Extensions for configuring ApiExplorer using an <see cref="IMvcCoreBuilder"/>.
+    /// </summary>
     public static class MvcApiExplorerMvcCoreBuilderExtensions
     {
+        /// <summary>
+        /// Configures <see cref="IMvcCoreBuilder"/> to use ApiExplorer.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcCoreBuilder"/>.</param>
+        /// <returns>The <see cref="IMvcCoreBuilder"/>.</returns>
         public static IMvcCoreBuilder AddApiExplorer(this IMvcCoreBuilder builder)
         {
             if (builder == null)

src/Mvc/Mvc.ApiExplorer/src/Microsoft.AspNetCore.Mvc.ApiExplorer.csproj

@@ -4,7 +4,6 @@
     <Description>ASP.NET Core MVC API explorer functionality for discovering metadata such as the list of controllers and actions, and their URLs and allowed HTTP methods.</Description>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;aspnetcoremvc</PackageTags>
   </PropertyGroup>

src/Mvc/Mvc.Core/src/ActionResultOfT.cs

@@ -53,11 +53,19 @@ namespace Microsoft.AspNetCore.Mvc
         /// </summary>
         public TValue Value { get; }
 
+        /// <summary>
+        /// Implictly converts the specified <paramref name="value"/> to an <see cref="ActionResult{TValue}"/>.
+        /// </summary>
+        /// <param name="value">The value to convert.</param>
         public static implicit operator ActionResult<TValue>(TValue value)
         {
             return new ActionResult<TValue>(value);
         }
 
+        /// <summary>
+        /// Implictly converts the specified <paramref name="result"/> to an <see cref="ActionResult{TValue}"/>.
+        /// </summary>
+        /// <param name="result">The <see cref="ActionResult"/>.</param>
         public static implicit operator ActionResult<TValue>(ActionResult result)
         {
             return new ActionResult<TValue>(result);

src/Mvc/Mvc.Core/src/ApiExplorer/ApiConventionResult.cs

@@ -13,12 +13,19 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
     /// </summary>
     public sealed class ApiConventionResult
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="ApiConventionResult"/>.
+        /// </summary>
+        /// <param name="responseMetadataProviders">The sequence of <see cref="IApiResponseMetadataProvider"/> that are associated with the action.</param>
         public ApiConventionResult(IReadOnlyList<IApiResponseMetadataProvider> responseMetadataProviders)
         {
             ResponseMetadataProviders = responseMetadataProviders ??
                 throw new ArgumentNullException(nameof(responseMetadataProviders));
         }
 
+        /// <summary>
+        /// Gets the sequence of <see cref="IApiResponseMetadataProvider"/> that are associated with the action.
+        /// </summary>
         public IReadOnlyList<IApiResponseMetadataProvider> ResponseMetadataProviders { get; }
 
         internal static bool TryGetApiConvention(

src/Mvc/Mvc.Core/src/ApiExplorer/ApiConventionTypeMatchAttribute.cs

@@ -17,11 +17,18 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
     [AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = false)]
     public sealed class ApiConventionTypeMatchAttribute : Attribute
     {
+        /// <summary>
+        /// Initialzes a new instance of <see cref="ApiConventionTypeMatchAttribute"/> with the specified <paramref name="matchBehavior"/>.
+        /// </summary>
+        /// <param name="matchBehavior">The <see cref="ApiConventionTypeMatchBehavior"/>.</param>
         public ApiConventionTypeMatchAttribute(ApiConventionTypeMatchBehavior matchBehavior)
         {
             MatchBehavior = matchBehavior;
         }
 
+        /// <summary>
+        /// Gets the <see cref="ApiConventionTypeMatchBehavior"/>.
+        /// </summary>
         public ApiConventionTypeMatchBehavior MatchBehavior { get; }
     }
 }

src/Mvc/Mvc.Core/src/ApplicationModels/ActionModel.cs

@@ -13,9 +13,17 @@ using Microsoft.Extensions.Internal;
 
 namespace Microsoft.AspNetCore.Mvc.ApplicationModels
 {
+    /// <summary>
+    /// An application model for controller actions.
+    /// </summary>
     [DebuggerDisplay("{DisplayName}")]
     public class ActionModel : ICommonModel, IFilterModel, IApiExplorerModel
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="ActionModel"/>.
+        /// </summary>
+        /// <param name="actionMethod">The action <see cref="MethodInfo"/>.</param>
+        /// <param name="attributes">The attributes associated with the action.</param>
         public ActionModel(
             MethodInfo actionMethod,
             IReadOnlyList<object> attributes)
@@ -41,6 +49,10 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             Selectors = new List<SelectorModel>();
         }
 
+        /// <summary>
+        /// Copy constructor for <see cref="ActionModel"/>.
+        /// </summary>
+        /// <param name="other">The <see cref="ActionModel"/> to copy.</param>
         public ActionModel(ActionModel other)
         {
             if (other == null)
@@ -67,8 +79,14 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             Selectors = new List<SelectorModel>(other.Selectors.Select(s => new SelectorModel(s)));
         }
 
+        /// <summary>
+        /// Gets the action <see cref="MethodInfo"/>.
+        /// </summary>
         public MethodInfo ActionMethod { get; }
 
+        /// <summary>
+        /// Gets the action name.
+        /// </summary>
         public string ActionName { get; set; }
 
         /// <summary>
@@ -83,6 +101,9 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         /// </remarks>
         public ApiExplorerModel ApiExplorer { get; set; }
 
+        /// <summary>
+        /// Gets the attributes associated with the action.
+        /// </summary>
         public IReadOnlyList<object> Attributes { get; }
 
         /// <summary>
@@ -90,8 +111,14 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         /// </summary>
         public ControllerModel Controller { get; set; }
 
+        /// <summary>
+        /// Gets the <see cref="IFilterMetadata"/> instances associated with the action.
+        /// </summary>
         public IList<IFilterMetadata> Filters { get; }
 
+        /// <summary>
+        /// Gets the parameters associated with this action.
+        /// </summary>
         public IList<ParameterModel> Parameters { get; }
 
         /// <summary>
@@ -144,6 +171,9 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         /// </summary>
         public IList<SelectorModel> Selectors { get; }
 
+        /// <summary>
+        /// Gets the action display name.
+        /// </summary>
         public string DisplayName
         {
             get

src/Mvc/Mvc.Core/src/ApplicationModels/ApiConventionApplicationModelConvention.cs

@@ -34,6 +34,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         /// </summary>
         public ProducesErrorResponseTypeAttribute DefaultErrorResponseType { get; }
 
+        /// <inheritdoc />
         public void Apply(ActionModel action)
         {
             if (action == null)
@@ -50,6 +51,14 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             DiscoverErrorResponseType(action);
         }
 
+        /// <summary>
+        /// Determines if this instance of <see cref="IActionModelConvention"/> applies to a specified <paramref name="action"/>.
+        /// </summary>
+        /// <param name="action">The <see cref="ActionModel"/>.</param>
+        /// <returns>
+        /// <see langword="true"/> if the convention applies, otherwise <see langword="false"/>.
+        /// Derived types may override this method to selectively apply this convention.
+        /// </returns>
         protected virtual bool ShouldApply(ActionModel action) => true;
 
         private static void DiscoverApiConvention(ActionModel action)

src/Mvc/Mvc.Core/src/ApplicationModels/ApiVisibilityConvention.cs

@@ -8,6 +8,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
     /// </summary>
     public class ApiVisibilityConvention : IActionModelConvention
     {
+        /// <inheritdoc />
         public void Apply(ActionModel action)
         {
             if (!ShouldApply(action))
@@ -22,6 +23,14 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             }
         }
 
+        /// <summary>
+        /// Determines if this instance of <see cref="IActionModelConvention"/> applies to a specified <paramref name="action"/>.
+        /// </summary>
+        /// <param name="action">The <see cref="ActionModel"/>.</param>
+        /// <returns>
+        /// <see langword="true"/> if the convention applies, otherwise <see langword="false"/>.
+        /// Derived types may override this method to selectively apply this convention.
+        /// </returns>
         protected virtual bool ShouldApply(ActionModel action) => true;
     }
 }

src/Mvc/Mvc.Core/src/ApplicationModels/ApplicationModel.cs

@@ -7,9 +7,15 @@ using Microsoft.AspNetCore.Mvc.Filters;
 
 namespace Microsoft.AspNetCore.Mvc.ApplicationModels
 {
+    /// <summary>
+    /// A model for configuring controllers in an MVC application.
+    /// </summary>
     [DebuggerDisplay("ApplicationModel: Controllers: {Controllers.Count}, Filters: {Filters.Count}")]
     public class ApplicationModel : IPropertyModel, IFilterModel, IApiExplorerModel
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="ApplicationModel"/>.
+        /// </summary>
         public ApplicationModel()
         {
             ApiExplorer = new ApiExplorerModel();
@@ -31,8 +37,14 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         /// </remarks>
         public ApiExplorerModel ApiExplorer { get; set; }
 
+        /// <summary>
+        /// Gets the <see cref="ControllerModel"/> instances.
+        /// </summary>
         public IList<ControllerModel> Controllers { get; }
 
+        /// <summary>
+        /// Gets the global <see cref="IFilterMetadata"/> instances.
+        /// </summary>
         public IList<IFilterMetadata> Filters { get; }
 
         /// <summary>

src/Mvc/Mvc.Core/src/ApplicationModels/ApplicationModelProviderContext.cs

@@ -12,6 +12,10 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
     /// </summary>
     public class ApplicationModelProviderContext
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="ApplicationModelProviderContext"/>.
+        /// </summary>
+        /// <param name="controllerTypes">The discovered controller <see cref="TypeInfo"/> instances.</param>
         public ApplicationModelProviderContext(IEnumerable<TypeInfo> controllerTypes)
         {
             if (controllerTypes == null)
@@ -22,6 +26,9 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             ControllerTypes = controllerTypes;
         }
 
+        /// <summary>
+        /// Gets the discovered controller <see cref="TypeInfo"/> instances.
+        /// </summary>
         public IEnumerable<TypeInfo> ControllerTypes { get; }
 
         /// <summary>

src/Mvc/Mvc.Core/src/ApplicationModels/AttributeRouteModel.cs

@@ -11,14 +11,24 @@ using Microsoft.AspNetCore.Routing;
 
 namespace Microsoft.AspNetCore.Mvc.ApplicationModels
 {
+    /// <summary>
+    /// A model for attribute routes.
+    /// </summary>
     public class AttributeRouteModel
     {
         private static readonly AttributeRouteModel _default = new AttributeRouteModel();
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="AttributeRoute"/>.
+        /// </summary>
         public AttributeRouteModel()
         {
         }
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="AttributeRoute"/> using the specified <paramref name="templateProvider"/>.
+        /// </summary>
+        /// <param name="templateProvider">The <see cref="IRouteTemplateProvider"/>.</param>
         public AttributeRouteModel(IRouteTemplateProvider templateProvider)
         {
             if (templateProvider == null)
@@ -32,6 +42,10 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             Name = templateProvider.Name;
         }
 
+        /// <summary>
+        /// Copy constructor for <see cref="AttributeRoute"/>.
+        /// </summary>
+        /// <param name="other">The <see cref="AttributeRouteModel"/> to copy.</param>
         public AttributeRouteModel(AttributeRouteModel other)
         {
             if (other == null)
@@ -47,12 +61,24 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             SuppressPathMatching = other.SuppressPathMatching;
         }
 
-        public IRouteTemplateProvider Attribute { get;}
+        /// <summary>
+        /// Gets the <see cref="IRouteTemplateProvider"/>.
+        /// </summary>
+        public IRouteTemplateProvider Attribute { get; }
 
+        /// <summary>
+        /// Gets or sets the attribute route template.
+        /// </summary>
         public string Template { get; set; }
 
+        /// <summary>
+        /// Gets or sets the route order.
+        /// </summary>
         public int? Order { get; set; }
 
+        /// <summary>
+        /// Gets or sets the route name.
+        /// </summary>
         public string Name { get; set; }
 
         /// <summary>
@@ -65,6 +91,9 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         /// </summary>
         public bool SuppressPathMatching { get; set; }
 
+        /// <summary>
+        /// Gets or sets a value that determines if this route template for this model overrides the route template at the parent scope.
+        /// </summary>
         public bool IsAbsoluteTemplate => Template != null && IsOverridePattern(Template);
 
         /// <summary>

src/Mvc/Mvc.Core/src/ApplicationModels/ClientErrorResultFilterConvention.cs

@@ -15,6 +15,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
     {
         private readonly ClientErrorResultFilterFactory _filterFactory = new ClientErrorResultFilterFactory();
 
+        /// <inheritdoc />
         public void Apply(ActionModel action)
         {
             if (action == null)
@@ -31,6 +32,14 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             action.Filters.Add(_filterFactory);
         }
 
+        /// <summary>
+        /// Determines if this instance of <see cref="IActionModelConvention"/> applies to a specified <paramref name="action"/>.
+        /// </summary>
+        /// <param name="action">The <see cref="ActionModel"/>.</param>
+        /// <returns>
+        /// <see langword="true"/> if the convention applies, otherwise <see langword="false"/>.
+        /// Derived types may override this method to selectively apply this convention.
+        /// </returns>
         protected virtual bool ShouldApply(ActionModel action) => true;
     }
 }

src/Mvc/Mvc.Core/src/ApplicationModels/ConsumesConstraintForFormFileParameterConvention.cs

@@ -14,6 +14,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
     /// </summary>
     public class ConsumesConstraintForFormFileParameterConvention : IActionModelConvention
     {
+        /// <inheritdoc />
         public void Apply(ActionModel action)
         {
             if (action == null)
@@ -29,6 +30,14 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             AddMultipartFormDataConsumesAttribute(action);
         }
 
+        /// <summary>
+        /// Determines if this instance of <see cref="IActionModelConvention"/> applies to a specified <paramref name="action"/>.
+        /// </summary>
+        /// <param name="action">The <see cref="ActionModel"/>.</param>
+        /// <returns>
+        /// <see langword="true"/> if the convention applies, otherwise <see langword="false"/>.
+        /// Derived types may override this method to selectively apply this convention.
+        /// </returns>
         protected virtual bool ShouldApply(ActionModel action) => true;
 
         // Internal for unit testing

src/Mvc/Mvc.Core/src/DependencyInjection/MvcCoreMvcBuilderExtensions.cs

@@ -42,6 +42,12 @@ namespace Microsoft.Extensions.DependencyInjection
             return builder;
         }
 
+        /// <summary>
+        /// Configures <see cref="FormatterMappings"/> for the specified <paramref name="builder"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcBuilder"/>.</param>
+        /// <param name="setupAction">An <see cref="Action"/> to configure the <see cref="FormatterMappings"/>.</param>
+        /// <returns>The <see cref="IMvcBuilder"/>.</returns>
         public static IMvcBuilder AddFormatterMappings(
             this IMvcBuilder builder,
             Action<FormatterMappings> setupAction)

src/Mvc/Mvc.Core/src/DependencyInjection/MvcCoreMvcCoreBuilderExtensions.cs

@@ -15,6 +15,9 @@ using Microsoft.Extensions.DependencyInjection.Extensions;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
+    /// <summary>
+    /// Extensions for configuring MVC using an <see cref="IMvcCoreBuilder"/>.
+    /// </summary>
     public static class MvcCoreMvcCoreBuilderExtensions
     {
         /// <summary>
@@ -41,12 +44,23 @@ namespace Microsoft.Extensions.DependencyInjection
             return builder;
         }
 
+        /// <summary>
+        /// Adds services to support <see cref="FormatterMappings"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcBuilder"/>.</param>
+        /// <returns>The <see cref="IMvcBuilder"/>.</returns>
         public static IMvcCoreBuilder AddFormatterMappings(this IMvcCoreBuilder builder)
         {
             AddFormatterMappingsServices(builder.Services);
             return builder;
         }
 
+        /// <summary>
+        /// Configures <see cref="FormatterMappings"/> for the specified <paramref name="setupAction"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcCoreBuilder"/>.</param>
+        /// <param name="setupAction">An <see cref="Action"/> to configure the <see cref="FormatterMappings"/>.</param>
+        /// <returns>The <see cref="IMvcBuilder"/>.</returns>
         public static IMvcCoreBuilder AddFormatterMappings(
             this IMvcCoreBuilder builder,
             Action<FormatterMappings> setupAction)
@@ -67,12 +81,23 @@ namespace Microsoft.Extensions.DependencyInjection
             services.TryAddSingleton<FormatFilter, FormatFilter>();
         }
 
+        /// <summary>
+        /// Configures authentication and authorization services for <paramref name="builder"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcCoreBuilder"/>.</param>
+        /// <returns>The <see cref="IMvcCoreBuilder"/>.</returns>
         public static IMvcCoreBuilder AddAuthorization(this IMvcCoreBuilder builder)
         {
             AddAuthorizationServices(builder.Services);
             return builder;
         }
 
+        /// <summary>
+        /// Configures authentication and authorization services for <paramref name="builder"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcCoreBuilder"/>.</param>
+        /// <param name="setupAction">An <see cref="Action"/> to configure the <see cref="AuthorizationOptions"/>.</param>
+        /// <returns>The <see cref="IMvcCoreBuilder"/>.</returns>
         public static IMvcCoreBuilder AddAuthorization(
             this IMvcCoreBuilder builder,
             Action<AuthorizationOptions> setupAction)

src/Mvc/Mvc.Cors/src/DependencyInjection/MvcCorsMvcCoreBuilderExtensions.cs

@@ -9,8 +9,16 @@ using Microsoft.Extensions.DependencyInjection.Extensions;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
+    /// <summary>
+    /// Extensions for configuring CORS using an <see cref="IMvcCoreBuilder"/>.
+    /// </summary>
     public static class MvcCorsMvcCoreBuilderExtensions
     {
+        /// <summary>
+        /// Configures <see cref="IMvcCoreBuilder"/> to use CORS.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcCoreBuilder"/>.</param>
+        /// <returns>The <see cref="IMvcCoreBuilder"/>.</returns>
         public static IMvcCoreBuilder AddCors(this IMvcCoreBuilder builder)
         {
             if (builder == null)
@@ -22,6 +30,12 @@ namespace Microsoft.Extensions.DependencyInjection
             return builder;
         }
 
+        /// <summary>
+        /// Configures <see cref="IMvcCoreBuilder"/> to use CORS.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcCoreBuilder"/>.</param>
+        /// <param name="setupAction">An <see cref="Action{MvcOptions}"/> to configure the provided <see cref="CorsOptions"/>.</param>
+        /// <returns>The <see cref="IMvcCoreBuilder"/>.</returns>
         public static IMvcCoreBuilder AddCors(
             this IMvcCoreBuilder builder,
             Action<CorsOptions> setupAction)
@@ -42,6 +56,12 @@ namespace Microsoft.Extensions.DependencyInjection
             return builder;
         }
 
+        /// <summary>
+        /// Configures <see cref="CorsOptions"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IMvcCoreBuilder"/>.</param>
+        /// <param name="setupAction">The configure action.</param>
+        /// <returns>The <see cref="IMvcCoreBuilder"/>.</returns>
         public static IMvcCoreBuilder ConfigureCors(
             this IMvcCoreBuilder builder,
             Action<CorsOptions> setupAction)

src/Mvc/Mvc.Cors/src/Microsoft.AspNetCore.Mvc.Cors.csproj

@@ -4,7 +4,6 @@
     <Description>ASP.NET Core MVC cross-origin resource sharing (CORS) features.</Description>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;aspnetcoremvc;cors</PackageTags>
   </PropertyGroup>

src/Mvc/Mvc.DataAnnotations/src/Microsoft.AspNetCore.Mvc.DataAnnotations.csproj

@@ -4,7 +4,6 @@
     <Description>ASP.NET Core MVC metadata and validation system using System.ComponentModel.DataAnnotations.</Description>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;aspnetcoremvc</PackageTags>
   </PropertyGroup>

src/Mvc/Mvc.Localization/src/Microsoft.AspNetCore.Mvc.Localization.csproj

@@ -7,7 +7,6 @@ Microsoft.AspNetCore.Mvc.Localization.IHtmlLocalizer<TResource>
 Microsoft.AspNetCore.Mvc.Localization.IViewLocalizer</Description>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;aspnetcoremvc;localization</PackageTags>
   </PropertyGroup>

src/Mvc/Mvc.NewtonsoftJson/src/Microsoft.AspNetCore.Mvc.NewtonsoftJson.csproj

@@ -3,7 +3,6 @@
   <PropertyGroup>
     <Description>ASP.NET Core MVC features that use Newtonsoft.Json. Includes input and output formatters for JSON and JSON PATCH.</Description>
     <TargetFramework>netcoreapp3.0</TargetFramework>
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;aspnetcoremvc;json</PackageTags>
     <IsShippingPackage>true</IsShippingPackage>

src/Mvc/Mvc/src/Microsoft.AspNetCore.Mvc.csproj

@@ -3,7 +3,6 @@
   <PropertyGroup>
     <Description>ASP.NET Core MVC is a web framework that gives you a powerful, patterns-based way to build dynamic websites and web APIs. ASP.NET Core MVC enables a clean separation of concerns and gives you full control over markup.</Description>
     <TargetFramework>netcoreapp3.0</TargetFramework>
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;aspnetcoremvc</PackageTags>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>