Change Icon.Sizes property from string to IList<string> per spec update

Co-authored-by: jozkee <16040868+jozkee@users.noreply.github.com>

Author: Copilot

src/ModelContextProtocol.Core/Protocol/Icon.cs

@@ -59,17 +59,17 @@ public sealed class Icon
     public string? MimeType { get; init; }
 
     /// <summary>
-    /// Gets or sets the optional size specification for the icon.
+    /// Gets or sets the optional size specifications for the icon.
     /// </summary>
     /// <remarks>
     /// <para>
     /// This can specify one or more sizes at which the icon file can be used.
-    /// Examples include "48x48", "any" for scalable formats like SVG, or "48x48 96x96" for multiple sizes.
+    /// Examples include "48x48", "any" for scalable formats like SVG.
     /// </para>
     /// <para>
     /// If not provided, clients should assume that the icon can be used at any size.
     /// </para>
     /// </remarks>
     [JsonPropertyName("sizes")]
-    public string? Sizes { get; init; }
+    public IList<string>? Sizes { get; init; }
 }

tests/ModelContextProtocol.Tests/Protocol/IconTests.cs

@@ -13,7 +13,7 @@ public static void Icon_SerializationRoundTrip_PreservesAllProperties()
         {
             Source = "https://example.com/icon.png",
             MimeType = "image/png",
-            Sizes = "48x48"
+            Sizes = new List<string> { "48x48" }
         };
 
         // Act - Serialize to JSON
@@ -58,7 +58,7 @@ public static void Icon_HasCorrectJsonPropertyNames()
         {
             Source = "https://example.com/icon.svg",
             MimeType = "image/svg+xml",
-            Sizes = "any"
+            Sizes = new List<string> { "any" }
         };
 
         string json = JsonSerializer.Serialize(icon, McpJsonUtilities.DefaultOptions);

tests/ModelContextProtocol.Tests/Protocol/ImplementationTests.cs

@@ -16,8 +16,8 @@ public static void Implementation_SerializationRoundTrip_PreservesAllProperties(
             Version = "1.0.0",
             Icons =
             [
-                new() { Source = "https://example.com/icon.png", MimeType = "image/png", Sizes = "48x48" },
-                new() { Source = "https://example.com/icon.svg", MimeType = "image/svg+xml", Sizes = "any" }
+                new() { Source = "https://example.com/icon.png", MimeType = "image/png", Sizes = new List<string> { "48x48" } },
+                new() { Source = "https://example.com/icon.svg", MimeType = "image/svg+xml", Sizes = new List<string> { "any" } }
             ],
             WebsiteUrl = "https://example.com"
         };

tests/ModelContextProtocol.Tests/Protocol/PromptTests.cs

@@ -16,7 +16,7 @@ public static void Prompt_SerializationRoundTrip_PreservesAllProperties()
             Description = "Review the provided code",
             Icons =
             [
-                new() { Source = "https://example.com/review-icon.svg", MimeType = "image/svg+xml", Sizes = "any" }
+                new() { Source = "https://example.com/review-icon.svg", MimeType = "image/svg+xml", Sizes = new List<string> { "any" } }
             ],
             Arguments =
             [

tests/ModelContextProtocol.Tests/Protocol/ResourceTests.cs

@@ -19,7 +19,7 @@ public static void Resource_SerializationRoundTrip_PreservesAllProperties()
             Size = 1024,
             Icons =
             [
-                new() { Source = "https://example.com/pdf-icon.png", MimeType = "image/png", Sizes = "32x32" }
+                new() { Source = "https://example.com/pdf-icon.png", MimeType = "image/png", Sizes = new List<string> { "32x32" } }
             ],
             Annotations = new Annotations { Audience = [Role.User] }
         };

tests/ModelContextProtocol.Tests/Protocol/ToolTests.cs

@@ -16,7 +16,7 @@ public static void Tool_SerializationRoundTrip_PreservesAllProperties()
             Description = "Get current weather information",
             Icons =
             [
-                new() { Source = "https://example.com/weather.png", MimeType = "image/png", Sizes = "48x48" }
+                new() { Source = "https://example.com/weather.png", MimeType = "image/png", Sizes = new List<string> { "48x48" } }
             ],
             Annotations = new ToolAnnotations
             {

tests/ModelContextProtocol.Tests/Server/McpServerToolTests.cs

@@ -683,8 +683,8 @@ public void SupportsIconsInCreateOptions()
     {
         var icons = new List<Icon>
         {
-            new() { Source = "https://example.com/icon.png", MimeType = "image/png", Sizes = "48x48" },
-            new() { Source = "https://example.com/icon.svg", MimeType = "image/svg+xml", Sizes = "any" }
+            new() { Source = "https://example.com/icon.png", MimeType = "image/png", Sizes = new List<string> { "48x48" } },
+            new() { Source = "https://example.com/icon.svg", MimeType = "image/svg+xml", Sizes = new List<string> { "any" } }
         };
 
         McpServerTool tool = McpServerTool.Create(() => "test", new McpServerToolCreateOptions
@@ -696,10 +696,14 @@ public void SupportsIconsInCreateOptions()
         Assert.Equal(2, tool.ProtocolTool.Icons.Count);
         Assert.Equal("https://example.com/icon.png", tool.ProtocolTool.Icons[0].Source);
         Assert.Equal("image/png", tool.ProtocolTool.Icons[0].MimeType);
-        Assert.Equal("48x48", tool.ProtocolTool.Icons[0].Sizes);
+        Assert.NotNull(tool.ProtocolTool.Icons[0].Sizes);
+        Assert.Single(tool.ProtocolTool.Icons[0].Sizes);
+        Assert.Equal("48x48", tool.ProtocolTool.Icons[0].Sizes[0]);
         Assert.Equal("https://example.com/icon.svg", tool.ProtocolTool.Icons[1].Source);
         Assert.Equal("image/svg+xml", tool.ProtocolTool.Icons[1].MimeType);
-        Assert.Equal("any", tool.ProtocolTool.Icons[1].Sizes);
+        Assert.NotNull(tool.ProtocolTool.Icons[1].Sizes);
+        Assert.Single(tool.ProtocolTool.Icons[1].Sizes);
+        Assert.Equal("any", tool.ProtocolTool.Icons[1].Sizes[0]);
     }
 
     [Fact]