Update new option binding handling

core/Azure.Mcp.Core/src/Commands/Subscription/SubscriptionCommand`2.cs

@@ -9,15 +9,10 @@
 namespace Azure.Mcp.Core.Commands.Subscription;
 
 public abstract class SubscriptionCommand<
-    [DynamicallyAccessedMembers(TrimAnnotations.CommandAnnotations)] TOptions, TResult>
+    [DynamicallyAccessedMembers(TrimAnnotations.CommandAnnotations)] TOptions, TResult>(ISubscriptionResolver subscriptionResolver)
      : AuthenticatedCommand<TOptions, TResult> where TOptions : class, ISubscriptionOption
 {
-    private readonly ISubscriptionResolver _subscriptionResolver;
-
-    protected SubscriptionCommand(ISubscriptionResolver subscriptionResolver)
-    {
-        _subscriptionResolver = subscriptionResolver;
-    }
+    private readonly ISubscriptionResolver _subscriptionResolver = subscriptionResolver;
 
     public override void ValidateOptions(TOptions options, ValidationResult validationResult)
     {

core/Microsoft.Mcp.Core/src/Commands/BaseCommand`2.cs

@@ -71,6 +71,11 @@ public virtual void PostBindOptions(TOptions options)
     {
     }
 
+    /// <summary>
+    /// Validates the options after they have been bound.
+    /// </summary>
+    /// <param name="options">The options to validate.</param>
+    /// <param name="validationResult">The validation result to populate.</param>
     public virtual void ValidateOptions(TOptions options, ValidationResult validationResult)
     {
     }

core/Microsoft.Mcp.Core/src/Extensions/CommandResultExtensions.cs

@@ -123,6 +123,23 @@ public static bool TryGetValue<T>(this CommandResult commandResult, string optio
         return GetValueOrDefaultImpl(commandResult, option);
     }
 
+    /// <summary>
+    /// Special version for GetValueOrDefault for new option binding as the Option is immutable once created.
+    /// <para>
+    /// The name-based lookup was needed because the static Option would be re-created in RegisterOptions when changing
+    /// requiredness. CommandResult result retrieval uses the Option instance references as a Dictionary key. So,
+    /// changing requiredness in RegisterOptions and using the static Option in BindOptions would break silently and
+    /// necessitated the name based retrieval. That is no longer necessary with the new option binding approach and
+    /// this more performant approach should be used.
+    /// </para>
+    /// </summary>
+    /// <typeparam name="T">The type of the option value</typeparam>
+    /// <param name="commandResult">The command result</param>
+    /// <param name="option">The option</param>
+    /// <returns>The value of the option, or the default value if not found or not set</returns>
+    internal static T? GetValueOrDefaultWithoutName<T>(this CommandResult commandResult, Option<T> option)
+        => GetValueOrDefaultImpl(commandResult, option);
+
     private static T? GetValueOrDefaultImpl<T>(CommandResult commandResult, Option<T> option)
     {
         ArgumentNullException.ThrowIfNull(commandResult);

core/Microsoft.Mcp.Core/src/Extensions/ParseResultExtensions.cs

@@ -16,6 +16,23 @@ public static bool TryGetValue<T>(this ParseResult parseResult, string optionNam
     public static T? GetValueOrDefault<T>(this ParseResult parseResult, Option<T> option)
         => GetValueOrDefault<T>(parseResult, option.Name);
 
+    /// <summary>
+    /// Special version for GetValueOrDefault for new option binding as the Option is immutable once created.
+    /// <para>
+    /// The name-based lookup was needed because the static Option would be re-created in RegisterOptions when changing
+    /// requiredness. ParseResult result retrieval uses the Option instance references as a Dictionary key. So,
+    /// changing requiredness in RegisterOptions and using the static Option in BindOptions would break silently and
+    /// necessitated the name based retrieval. That is no longer necessary with the new option binding approach and
+    /// this more performant approach should be used.
+    /// </para>
+    /// </summary>
+    /// <typeparam name="T">The type of the option value</typeparam>
+    /// <param name="parseResult">The parse result</param>
+    /// <param name="option">The option</param>
+    /// <returns>The value of the option, or the default value if not found or not set</returns>
+    internal static T? GetValueOrDefaultWithoutName<T>(this ParseResult parseResult, Option<T> option)
+        => parseResult.CommandResult.GetValueOrDefaultWithoutName<T>(option);
+
     /// <summary>
     /// Gets the value of an option by name, returning default if not found or not set
     /// </summary>

core/Microsoft.Mcp.Core/src/Options/OptionAttribute.cs

@@ -40,11 +40,21 @@ public OptionAttribute(string description)
     /// </summary>
     public string? Name { get; init; }
 
+    /// <summary>
+    /// Additional CLI option names (without the "--" prefix).
+    /// </summary>
+    public string[]? Aliases { get; init; }
+
     /// <summary>
     /// A description of what the option controls. Used in help text and by AI agents.
     /// </summary>
     public string? Description { get; init; }
 
+    /// <summary>
+    /// A default value for the option when a value is not provided. Must match the property type being attributed.
+    /// </summary>
+    public object? DefaultValue { get; init; }
+
     /// <summary>
     /// Whether the option is hidden from help output.
     /// </summary>