Fix missing using directives and clarify McpMetaAttribute documentation

Co-authored-by: stephentoub <[email protected]>

Author: Copilot

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerPrompt.cs

@@ -5,6 +5,7 @@
 using System.Diagnostics;
 using System.Reflection;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 
 namespace ModelContextProtocol.Server;
 

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerResource.cs

@@ -9,6 +9,7 @@
 using System.Runtime.CompilerServices;
 using System.Text;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 using System.Text.RegularExpressions;
 
 namespace ModelContextProtocol.Server;

src/ModelContextProtocol.Core/Server/McpMetaAttribute.cs

@@ -50,8 +50,9 @@ public McpMetaAttribute()
     /// Gets or sets the value of the metadata entry.
     /// </summary>
     /// <remarks>
-    /// This value is stored as a string in the metadata object. Complex values should be
-    /// serialized to JSON strings if needed.
+    /// This value is stored as a string in the metadata object. For complex values, use the
+    /// <see cref="McpServerToolCreateOptions.Meta"/>, <see cref="McpServerPromptCreateOptions.Meta"/>, 
+    /// or <see cref="McpServerResourceCreateOptions.Meta"/> property to provide a JsonObject directly.
     /// </remarks>
     public required string Value { get; set; }
 }