Add McpServerToolAttribute.UseStructuredContent

Author: stephentoub

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerTool.cs

@@ -232,6 +232,8 @@ private static McpServerToolCreateOptions DeriveOptions(MethodInfo method, McpSe
             {
                 newOptions.ReadOnly ??= readOnly;
             }
+
+            newOptions.UseStructuredContent = toolAttr.UseStructuredContent;
         }
 
         if (method.GetCustomAttribute<DescriptionAttribute>() is { } descAttr)

src/ModelContextProtocol.Core/Server/McpServerToolAttribute.cs

@@ -240,4 +240,13 @@ public bool ReadOnly
         get => _readOnly ?? ReadOnlyDefault; 
         set => _readOnly = value; 
     }
+
+    /// <summary>
+    /// Gets or sets whether the tool should report an output schema for structured content.
+    /// </summary>
+    /// <remarks>
+    /// When enabled, the tool will attempt to populate the <see cref="Tool.OutputSchema"/>
+    /// and provide structured content in the <see cref="CallToolResponse.StructuredContent"/> property.
+    /// </remarks>
+    public bool UseStructuredContent { get; set; }
 }