Fix tests and a bit of cleanup

Author: stephentoub

src/ModelContextProtocol.Core/Protocol/ClientCapabilities.cs

@@ -47,7 +47,7 @@ public sealed class ClientCapabilities
     /// </para>
     /// <para>
     /// The server can use <see cref="McpServer.RequestRootsAsync"/> to request the list of
-    /// available roots from the client, which will trigger the client's <see cref="ModelContextProtocol.Client.McpClientHandlers.RootsHandler"/>.
+    /// available roots from the client, which will trigger the client's <see cref="McpClientHandlers.RootsHandler"/>.
     /// </para>
     /// </remarks>
     [JsonPropertyName("roots")]

src/ModelContextProtocol.Core/Protocol/ElicitationCapability.cs

@@ -13,7 +13,7 @@ namespace ModelContextProtocol.Protocol;
 /// </para>
 /// <para>
 /// When this capability is enabled, an MCP server can request the client to provide additional information
-/// during interactions. The client must set a <see cref="ModelContextProtocol.Client.McpClientHandlers.ElicitationHandler"/> to process these requests.
+/// during interactions. The client must set a <see cref="McpClientHandlers.ElicitationHandler"/> to process these requests.
 /// </para>
 /// <para>
 /// This class is intentionally empty as the Model Context Protocol specification does not

src/ModelContextProtocol.Core/Protocol/SamplingCapability.cs

@@ -14,7 +14,7 @@ namespace ModelContextProtocol.Protocol;
 /// </para>
 /// <para>
 /// When this capability is enabled, an MCP server can request the client to generate content
-/// using an AI model. The client must set a <see cref="ModelContextProtocol.Client.McpClientHandlers.SamplingHandler"/> to process these requests.
+/// using an AI model. The client must set a <see cref="McpClientHandlers.SamplingHandler"/> to process these requests.
 /// </para>
 /// <para>
 /// This class is intentionally empty as the Model Context Protocol specification does not

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerTool.cs

@@ -364,16 +364,12 @@ internal static IReadOnlyList<object> CreateMetadata(MethodInfo method)
     /// <returns>A <see cref="JsonObject"/> with metadata, or null if no metadata is present.</returns>
     internal static JsonObject? CreateMetaFromAttributes(MethodInfo method, JsonObject? meta = null, JsonSerializerOptions? serializerOptions = null)
     {
-        // Get all McpMetaAttribute instances from the method.
-        var metaAttributes = method.GetCustomAttributes<McpMetaAttribute>();
-        
-        foreach (var attr in metaAttributes)
+        // Transfer all McpMetaAttribute instances to the Meta JsonObject, ignoring any that would overwrite existing properties.
+        foreach (var attr in method.GetCustomAttributes<McpMetaAttribute>())
         {
-            meta ??= [];
-            if (!meta.ContainsKey(attr.Name))
+            if (meta?.ContainsKey(attr.Name) is not true)
             {
-                // Parse the JSON string value into a JsonNode
-                meta[attr.Name] = JsonNode.Parse(attr.Value);
+                (meta ??= [])[attr.Name] = JsonNode.Parse(attr.Value);
             }
         }
 

src/ModelContextProtocol.Core/Server/McpMetaAttribute.cs

@@ -8,11 +8,15 @@ namespace ModelContextProtocol.Server;
 /// </summary>
 /// <remarks>
 /// <para>
-/// This attribute can be applied multiple times to a method to specify multiple key/value pairs
-/// of metadata. The metadata is used to populate the <see cref="Tool.Meta"/>, <see cref="Prompt.Meta"/>,
+/// The metadata is used to populate the <see cref="Tool.Meta"/>, <see cref="Prompt.Meta"/>,
 /// or <see cref="Resource.Meta"/> property of the corresponding primitive.
 /// </para>
 /// <para>
+/// This attribute can be applied multiple times to a method to specify multiple key/value pairs
+/// of metadata. However, the same key should not be used more than once; doing so will result
+/// in undefined behavior.
+/// </para>
+/// <para>
 /// Metadata can be used to attach additional information to primitives, such as model preferences,
 /// version information, or other custom data that should be communicated to MCP clients.
 /// </para>
@@ -22,10 +26,7 @@ namespace ModelContextProtocol.Server;
 /// [McpMeta("model", "\"gpt-4o\"")]
 /// [McpMeta("version", "\"1.0\"")]
 /// [McpMeta("priority", "5")]
-/// public string MyTool(string input)
-/// {
-///     return $"Processed: {input}";
-/// }
+/// public string MyTool(string input) => $"Processed: {input}";
 /// </code>
 /// </example>
 /// </remarks>

src/ModelContextProtocol.Core/Server/McpServerPromptCreateOptions.cs

@@ -2,6 +2,7 @@
 using ModelContextProtocol.Protocol;
 using System.ComponentModel;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 
 namespace ModelContextProtocol.Server;
 
@@ -91,15 +92,15 @@ public sealed class McpServerPromptCreateOptions
     /// </summary>
     /// <remarks>
     /// <para>
-    /// This <see cref="System.Text.Json.Nodes.JsonObject"/> is used to seed the <see cref="Prompt.Meta"/> property. Any metadata from
+    /// This <see cref="JsonObject"/> is used to seed the <see cref="Prompt.Meta"/> property. Any metadata from
     /// <see cref="McpMetaAttribute"/> instances on the method will be added to this object, but
-    /// properties already present in this <see cref="System.Text.Json.Nodes.JsonObject"/> will not be overwritten.
+    /// properties already present in this <see cref="JsonObject"/> will not be overwritten.
     /// </para>
     /// <para>
     /// Implementations must not make assumptions about its contents.
     /// </para>
     /// </remarks>
-    public System.Text.Json.Nodes.JsonObject? Meta { get; set; }
+    public JsonObject? Meta { get; set; }
 
     /// <summary>
     /// Creates a shallow clone of the current <see cref="McpServerPromptCreateOptions"/> instance.

src/ModelContextProtocol.Core/Server/McpServerResourceCreateOptions.cs

@@ -2,6 +2,7 @@
 using ModelContextProtocol.Protocol;
 using System.ComponentModel;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 
 namespace ModelContextProtocol.Server;
 
@@ -106,15 +107,15 @@ public sealed class McpServerResourceCreateOptions
     /// </summary>
     /// <remarks>
     /// <para>
-    /// This <see cref="System.Text.Json.Nodes.JsonObject"/> is used to seed the <see cref="Resource.Meta"/> property. Any metadata from
+    /// This <see cref="JsonObject"/> is used to seed the <see cref="Resource.Meta"/> property. Any metadata from
     /// <see cref="McpMetaAttribute"/> instances on the method will be added to this object, but
-    /// properties already present in this <see cref="System.Text.Json.Nodes.JsonObject"/> will not be overwritten.
+    /// properties already present in this <see cref="JsonObject"/> will not be overwritten.
     /// </para>
     /// <para>
     /// Implementations must not make assumptions about its contents.
     /// </para>
     /// </remarks>
-    public System.Text.Json.Nodes.JsonObject? Meta { get; set; }
+    public JsonObject? Meta { get; set; }
 
     /// <summary>
     /// Creates a shallow clone of the current <see cref="McpServerResourceCreateOptions"/> instance.

src/ModelContextProtocol.Core/Server/McpServerToolCreateOptions.cs

@@ -2,6 +2,7 @@
 using ModelContextProtocol.Protocol;
 using System.ComponentModel;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 
 namespace ModelContextProtocol.Server;
 
@@ -177,15 +178,15 @@ public sealed class McpServerToolCreateOptions
     /// </summary>
     /// <remarks>
     /// <para>
-    /// This <see cref="System.Text.Json.Nodes.JsonObject"/> is used to seed the <see cref="Tool.Meta"/> property. Any metadata from
+    /// This <see cref="JsonObject"/> is used to seed the <see cref="Tool.Meta"/> property. Any metadata from
     /// <see cref="McpMetaAttribute"/> instances on the method will be added to this object, but
-    /// properties already present in this <see cref="System.Text.Json.Nodes.JsonObject"/> will not be overwritten.
+    /// properties already present in this <see cref="JsonObject"/> will not be overwritten.
     /// </para>
     /// <para>
     /// Implementations must not make assumptions about its contents.
     /// </para>
     /// </remarks>
-    public System.Text.Json.Nodes.JsonObject? Meta { get; set; }
+    public JsonObject? Meta { get; set; }
 
     /// <summary>
     /// Creates a shallow clone of the current <see cref="McpServerToolCreateOptions"/> instance.

tests/ModelContextProtocol.Tests/Server/McpMetaAttributeTests.cs

@@ -1,4 +1,5 @@
 using ModelContextProtocol.Server;
+using System.Text.Json;
 using System.Text.Json.Nodes;
 
 namespace ModelContextProtocol.Tests.Server;
@@ -193,9 +194,15 @@ public void McpMetaAttribute_NonStringValues_Serialized()
         var method = typeof(TestToolNonStringMetaClass).GetMethod(nameof(TestToolNonStringMetaClass.ToolWithNonStringMeta))!;
         var tool = McpServerTool.Create(method, target: null);
         Assert.NotNull(tool.ProtocolTool.Meta);
+
         Assert.Equal("42", tool.ProtocolTool.Meta["intValue"]?.ToString());
-        Assert.Equal("True", tool.ProtocolTool.Meta["boolValue"]?.ToString());
+        Assert.Equal(JsonValueKind.Number, tool.ProtocolTool.Meta["intValue"]?.GetValueKind());
+
+        Assert.Equal("true", tool.ProtocolTool.Meta["boolValue"]?.ToString());
+        Assert.Equal(JsonValueKind.True, tool.ProtocolTool.Meta["boolValue"]?.GetValueKind());
+
         Assert.Equal("1", tool.ProtocolTool.Meta["enumValue"]?.ToString());
+        Assert.Equal(JsonValueKind.Number, tool.ProtocolTool.Meta["enumValue"]?.GetValueKind());
     }
 
     [Fact]