Implement SEP-973: Icons and metadata support for Implementations, Resources, Tools, and Prompts (#802)

* Initial plan

* Initial plan for SEP-973 implementation

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Implement SEP-973: Add Icon class and icon support to Implementation, Resource, Tool, and Prompt

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Complete SEP-973 implementation with documentation and fix property consistency

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Address code review feedback: improve tests, remove docs, split test files

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Fix tests to use S.T.J. source generator

* Styling fixes

* Simplify Icons property documentation as suggested in code review

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Rename Icon.Src property to Icon.Source for more .NET-y naming

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Add icon support to McpServerTool infrastructure and attributes

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Cleanup

* Refactor icon tests to use Delegate overload instead of MethodInfo pattern

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

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

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

* Add icon support to Prompts and Resources (CreateOptions and Attributes)

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Add client-server integration tests for Icons and WebsiteUrl

Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>

* Fix nullability warnings

* Revert "Add client-server integration tests for Icons and WebsiteUrl"

This reverts commit f37de15569e54e86a0709121c9bdf80c5045511c.

* More nullability fixes

* Add more tests

* Address code review feedback: add Theme property, fix docs, improve test patterns

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

* Update Icon tests to exercise Theme property

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

* Add Theme property assertions to client-server integration tests

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

* Fix nullability

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MackinnonBuck <10456961+MackinnonBuck@users.noreply.github.com>
Co-authored-by: Mackinnon Buck <mackinnon.buck@gmail.com>
Co-authored-by: jozkee <16040868+jozkee@users.noreply.github.com>
Co-authored-by: David Cantú <dacantu@microsoft.com>

tests/ModelContextProtocol.Tests/Protocol/IconTests.cs

@@ -0,0 +1,95 @@
+using ModelContextProtocol.Protocol;
+using System.Text.Json;
+
+namespace ModelContextProtocol.Tests.Protocol;
+
+public static class IconTests
+{
+    [Fact]
+    public static void Icon_SerializationRoundTrip_PreservesAllProperties()
+    {
+        // Arrange
+        var original = new Icon
+        {
+            Source = "https://example.com/icon.png",
+            MimeType = "image/png",
+            Sizes = new List<string> { "48x48" },
+            Theme = "light"
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Icon>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Source, deserialized.Source);
+        Assert.Equal(original.MimeType, deserialized.MimeType);
+        Assert.Equal(original.Sizes, deserialized.Sizes);
+        Assert.Equal(original.Theme, deserialized.Theme);
+    }
+
+    [Fact]
+    public static void Icon_SerializationRoundTrip_WithOnlyRequiredProperties()
+    {
+        // Arrange
+        var original = new Icon
+        {
+            Source = "data:image/svg+xml;base64,PHN2Zy4uLjwvc3ZnPg=="
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Icon>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Source, deserialized.Source);
+        Assert.Equal(original.MimeType, deserialized.MimeType);
+        Assert.Equal(original.Sizes, deserialized.Sizes);
+        Assert.Null(deserialized.Theme);
+    }
+
+    [Fact]
+    public static void Icon_HasCorrectJsonPropertyNames()
+    {
+        var icon = new Icon
+        {
+            Source = "https://example.com/icon.svg",
+            MimeType = "image/svg+xml",
+            Sizes = new List<string> { "any" },
+            Theme = "dark"
+        };
+
+        string json = JsonSerializer.Serialize(icon, McpJsonUtilities.DefaultOptions);
+
+        Assert.Contains("\"src\":", json);
+        Assert.Contains("\"mimeType\":", json);
+        Assert.Contains("\"sizes\":", json);
+        Assert.Contains("\"theme\":", json);
+    }
+
+    [Theory]
+    [InlineData("""{}""")]
+    [InlineData("""{"mimeType":"image/png"}""")]
+    [InlineData("""{"sizes":"48x48"}""")]
+    [InlineData("""{"mimeType":"image/png","sizes":"48x48"}""")]
+    public static void Icon_DeserializationWithMissingSrc_ThrowsJsonException(string invalidJson)
+    {
+        Assert.Throws<JsonException>(() => JsonSerializer.Deserialize<Icon>(invalidJson, McpJsonUtilities.DefaultOptions));
+    }
+
+    [Theory]
+    [InlineData("false")]
+    [InlineData("true")]
+    [InlineData("42")]
+    [InlineData("[]")]
+    public static void Icon_DeserializationWithInvalidJson_ThrowsJsonException(string invalidJson)
+    {
+        Assert.Throws<JsonException>(() => JsonSerializer.Deserialize<Icon>(invalidJson, McpJsonUtilities.DefaultOptions));
+    }
+}

tests/ModelContextProtocol.Tests/Protocol/ImplementationTests.cs

@@ -0,0 +1,105 @@
+using ModelContextProtocol.Protocol;
+using System.Text.Json;
+
+namespace ModelContextProtocol.Tests.Protocol;
+
+public static class ImplementationTests
+{
+    [Fact]
+    public static void Implementation_SerializationRoundTrip_PreservesAllProperties()
+    {
+        // Arrange
+        var original = new Implementation
+        {
+            Name = "test-server",
+            Title = "Test MCP Server",
+            Version = "1.0.0",
+            Icons =
+            [
+                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"
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON  
+        var deserialized = JsonSerializer.Deserialize<Implementation>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Name, deserialized.Name);
+        Assert.Equal(original.Title, deserialized.Title);
+        Assert.Equal(original.Version, deserialized.Version);
+        Assert.Equal(original.WebsiteUrl, deserialized.WebsiteUrl);
+        Assert.NotNull(deserialized.Icons);
+        Assert.Equal(original.Icons.Count, deserialized.Icons.Count);
+        
+        for (int i = 0; i < original.Icons.Count; i++)
+        {
+            Assert.Equal(original.Icons[i].Source, deserialized.Icons[i].Source);
+            Assert.Equal(original.Icons[i].MimeType, deserialized.Icons[i].MimeType);
+            Assert.Equal(original.Icons[i].Sizes, deserialized.Icons[i].Sizes);
+        }
+    }
+
+    [Fact]
+    public static void Implementation_SerializationRoundTrip_WithoutOptionalProperties()
+    {
+        // Arrange
+        var original = new Implementation
+        {
+            Name = "simple-server",
+            Version = "1.0.0"
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Implementation>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Name, deserialized.Name);
+        Assert.Equal(original.Title, deserialized.Title);
+        Assert.Equal(original.Version, deserialized.Version);
+        Assert.Equal(original.Icons, deserialized.Icons);
+        Assert.Equal(original.WebsiteUrl, deserialized.WebsiteUrl);
+    }
+
+    [Fact]
+    public static void Implementation_HasCorrectJsonPropertyNames()
+    {
+        var implementation = new Implementation
+        {
+            Name = "test-server",
+            Title = "Test Server",
+            Version = "1.0.0",
+            Icons = [new() { Source = "https://example.com/icon.png" }],
+            WebsiteUrl = "https://example.com"
+        };
+
+        string json = JsonSerializer.Serialize(implementation, McpJsonUtilities.DefaultOptions);
+
+        Assert.Contains("\"name\":", json);
+        Assert.Contains("\"title\":", json);
+        Assert.Contains("\"version\":", json);
+        Assert.Contains("\"icons\":", json);
+        Assert.Contains("\"websiteUrl\":", json);
+    }
+
+    [Theory]
+    [InlineData("""{}""")]
+    [InlineData("""{"title":"Test Server"}""")]
+    [InlineData("""{"name":"test-server"}""")]
+    [InlineData("""{"version":"1.0.0"}""")]
+    [InlineData("""{"title":"Test Server","version":"1.0.0"}""")]
+    [InlineData("""{"name":"test-server","title":"Test Server"}""")]
+    public static void Implementation_DeserializationWithMissingRequiredProperties_ThrowsJsonException(string invalidJson)
+    {
+        Assert.Throws<JsonException>(() => JsonSerializer.Deserialize<Implementation>(invalidJson, McpJsonUtilities.DefaultOptions));
+    }
+}

tests/ModelContextProtocol.Tests/Protocol/PromptTests.cs

@@ -0,0 +1,97 @@
+using ModelContextProtocol.Protocol;
+using System.Text.Json;
+
+namespace ModelContextProtocol.Tests.Protocol;
+
+public static class PromptTests
+{
+    [Fact]
+    public static void Prompt_SerializationRoundTrip_PreservesAllProperties()
+    {
+        // Arrange
+        var original = new Prompt
+        {
+            Name = "code_review",
+            Title = "Code Review Prompt",
+            Description = "Review the provided code",
+            Icons =
+            [
+                new() { Source = "https://example.com/review-icon.svg", MimeType = "image/svg+xml", Sizes = new List<string> { "any" } }
+            ],
+            Arguments =
+            [
+                new() { Name = "code", Description = "The code to review", Required = true }
+            ]
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Prompt>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Name, deserialized.Name);
+        Assert.Equal(original.Title, deserialized.Title);
+        Assert.Equal(original.Description, deserialized.Description);
+        Assert.NotNull(deserialized.Icons);
+        Assert.Equal(original.Icons.Count, deserialized.Icons.Count);
+        Assert.Equal(original.Icons[0].Source, deserialized.Icons[0].Source);
+        Assert.Equal(original.Icons[0].MimeType, deserialized.Icons[0].MimeType);
+        Assert.Equal(original.Icons[0].Sizes, deserialized.Icons[0].Sizes);
+        Assert.NotNull(deserialized.Arguments);
+        Assert.Equal(original.Arguments.Count, deserialized.Arguments.Count);
+        Assert.Equal(original.Arguments[0].Name, deserialized.Arguments[0].Name);
+        Assert.Equal(original.Arguments[0].Description, deserialized.Arguments[0].Description);
+        Assert.Equal(original.Arguments[0].Required, deserialized.Arguments[0].Required);
+    }
+
+    [Fact]
+    public static void Prompt_SerializationRoundTrip_WithMinimalProperties()
+    {
+        // Arrange
+        var original = new Prompt
+        {
+            Name = "simple_prompt"
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Prompt>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Name, deserialized.Name);
+        Assert.Equal(original.Title, deserialized.Title);
+        Assert.Equal(original.Description, deserialized.Description);
+        Assert.Equal(original.Icons, deserialized.Icons);
+        Assert.Equal(original.Arguments, deserialized.Arguments);
+    }
+
+    [Fact]
+    public static void Prompt_HasCorrectJsonPropertyNames()
+    {
+        var prompt = new Prompt
+        {
+            Name = "test_prompt",
+            Title = "Test Prompt",
+            Description = "A test prompt",
+            Icons = [new() { Source = "https://example.com/icon.webp" }],
+            Arguments =
+            [
+                new() { Name = "input", Description = "Input parameter" }
+            ]
+        };
+
+        string json = JsonSerializer.Serialize(prompt, McpJsonUtilities.DefaultOptions);
+
+        Assert.Contains("\"name\":", json);
+        Assert.Contains("\"title\":", json);
+        Assert.Contains("\"description\":", json);
+        Assert.Contains("\"icons\":", json);
+        Assert.Contains("\"arguments\":", json);
+    }
+}

tests/ModelContextProtocol.Tests/Protocol/ResourceTests.cs

@@ -0,0 +1,104 @@
+using ModelContextProtocol.Protocol;
+using System.Text.Json;
+
+namespace ModelContextProtocol.Tests.Protocol;
+
+public static class ResourceTests
+{
+    [Fact]
+    public static void Resource_SerializationRoundTrip_PreservesAllProperties()
+    {
+        // Arrange
+        var original = new Resource
+        {
+            Name = "document.pdf",
+            Title = "Important Document",
+            Uri = "file:///path/to/document.pdf",
+            Description = "An important document",
+            MimeType = "application/pdf",
+            Size = 1024,
+            Icons =
+            [
+                new() { Source = "https://example.com/pdf-icon.png", MimeType = "image/png", Sizes = new List<string> { "32x32" } }
+            ],
+            Annotations = new Annotations { Audience = [Role.User] }
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Resource>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Name, deserialized.Name);
+        Assert.Equal(original.Title, deserialized.Title);
+        Assert.Equal(original.Uri, deserialized.Uri);
+        Assert.Equal(original.Description, deserialized.Description);
+        Assert.Equal(original.MimeType, deserialized.MimeType);
+        Assert.Equal(original.Size, deserialized.Size);
+        Assert.NotNull(deserialized.Icons);
+        Assert.Equal(original.Icons.Count, deserialized.Icons.Count);
+        Assert.Equal(original.Icons[0].Source, deserialized.Icons[0].Source);
+        Assert.Equal(original.Icons[0].MimeType, deserialized.Icons[0].MimeType);
+        Assert.Equal(original.Icons[0].Sizes, deserialized.Icons[0].Sizes);
+        Assert.NotNull(deserialized.Annotations);
+        Assert.Equal(original.Annotations.Audience, deserialized.Annotations.Audience);
+    }
+
+    [Fact]
+    public static void Resource_SerializationRoundTrip_WithMinimalProperties()
+    {
+        // Arrange
+        var original = new Resource
+        {
+            Name = "data.json",
+            Uri = "file:///path/to/data.json"
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Resource>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Name, deserialized.Name);
+        Assert.Equal(original.Title, deserialized.Title);
+        Assert.Equal(original.Uri, deserialized.Uri);
+        Assert.Equal(original.Description, deserialized.Description);
+        Assert.Equal(original.MimeType, deserialized.MimeType);
+        Assert.Equal(original.Size, deserialized.Size);
+        Assert.Equal(original.Icons, deserialized.Icons);
+        Assert.Equal(original.Annotations, deserialized.Annotations);
+    }
+
+    [Fact]
+    public static void Resource_HasCorrectJsonPropertyNames()
+    {
+        var resource = new Resource
+        {
+            Name = "test_resource",
+            Title = "Test Resource",
+            Uri = "file:///test",
+            Description = "A test resource",
+            MimeType = "text/plain",
+            Size = 512,
+            Icons = new List<Icon> { new() { Source = "https://example.com/icon.svg" } },
+            Annotations = new Annotations { Audience = [Role.User] }
+        };
+
+        string json = JsonSerializer.Serialize(resource, McpJsonUtilities.DefaultOptions);
+
+        Assert.Contains("\"name\":", json);
+        Assert.Contains("\"title\":", json);
+        Assert.Contains("\"uri\":", json);
+        Assert.Contains("\"description\":", json);
+        Assert.Contains("\"mimeType\":", json);
+        Assert.Contains("\"size\":", json);
+        Assert.Contains("\"icons\":", json);
+        Assert.Contains("\"annotations\":", json);
+    }
+}

tests/ModelContextProtocol.Tests/Protocol/ToolTests.cs

@@ -0,0 +1,94 @@
+using ModelContextProtocol.Protocol;
+using System.Text.Json;
+
+namespace ModelContextProtocol.Tests.Protocol;
+
+public static class ToolTests
+{
+    [Fact]
+    public static void Tool_SerializationRoundTrip_PreservesAllProperties()
+    {
+        // Arrange
+        var original = new Tool
+        {
+            Name = "get_weather",
+            Title = "Get Weather",
+            Description = "Get current weather information",
+            Icons =
+            [
+                new() { Source = "https://example.com/weather.png", MimeType = "image/png", Sizes = new List<string> { "48x48" } }
+            ],
+            Annotations = new ToolAnnotations
+            {
+                Title = "Weather Tool",
+                ReadOnlyHint = true
+            }
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Tool>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Name, deserialized.Name);
+        Assert.Equal(original.Title, deserialized.Title);
+        Assert.Equal(original.Description, deserialized.Description);
+        Assert.NotNull(deserialized.Icons);
+        Assert.Equal(original.Icons.Count, deserialized.Icons.Count);
+        Assert.Equal(original.Icons[0].Source, deserialized.Icons[0].Source);
+        Assert.Equal(original.Icons[0].MimeType, deserialized.Icons[0].MimeType);
+        Assert.Equal(original.Icons[0].Sizes, deserialized.Icons[0].Sizes);
+        Assert.NotNull(deserialized.Annotations);
+        Assert.Equal(original.Annotations.Title, deserialized.Annotations.Title);
+        Assert.Equal(original.Annotations.ReadOnlyHint, deserialized.Annotations.ReadOnlyHint);
+    }
+
+    [Fact]
+    public static void Tool_SerializationRoundTrip_WithMinimalProperties()
+    {
+        // Arrange
+        var original = new Tool
+        {
+            Name = "calculate"
+        };
+
+        // Act - Serialize to JSON
+        string json = JsonSerializer.Serialize(original, McpJsonUtilities.DefaultOptions);
+        
+        // Act - Deserialize back from JSON
+        var deserialized = JsonSerializer.Deserialize<Tool>(json, McpJsonUtilities.DefaultOptions);
+
+        // Assert
+        Assert.NotNull(deserialized);
+        Assert.Equal(original.Name, deserialized.Name);
+        Assert.Equal(original.Title, deserialized.Title);
+        Assert.Equal(original.Description, deserialized.Description);
+        Assert.Equal(original.Icons, deserialized.Icons);
+        Assert.Equal(original.Annotations, deserialized.Annotations);
+    }
+
+    [Fact]
+    public static void Tool_HasCorrectJsonPropertyNames()
+    {
+        var tool = new Tool
+        {
+            Name = "test_tool",
+            Title = "Test Tool",
+            Description = "A test tool",
+            Icons = [new() { Source = "https://example.com/icon.png" }],
+            Annotations = new ToolAnnotations { Title = "Annotation Title" }
+        };
+
+        string json = JsonSerializer.Serialize(tool, McpJsonUtilities.DefaultOptions);
+
+        Assert.Contains("\"name\":", json);
+        Assert.Contains("\"title\":", json);
+        Assert.Contains("\"description\":", json);
+        Assert.Contains("\"icons\":", json);
+        Assert.Contains("\"annotations\":", json);
+        Assert.Contains("\"inputSchema\":", json);
+    }
+}