Add explicit [Experimental] protected constructors to McpClient and McpServer

src/ModelContextProtocol.Core/Client/McpClient.cs

@@ -1,4 +1,5 @@
-using ModelContextProtocol.Protocol;
+using System.Diagnostics.CodeAnalysis;
+using ModelContextProtocol.Protocol;
 
 namespace ModelContextProtocol.Client;
 
@@ -7,6 +8,14 @@ namespace ModelContextProtocol.Client;
 /// </summary>
 public abstract partial class McpClient : McpSession
 {
+    /// <summary>
+    /// Initializes a new instance of the <see cref="McpClient"/> class.
+    /// </summary>
+    [Experimental(Experimentals.Tasks_DiagnosticId, UrlFormat = Experimentals.Tasks_Url)]
+    protected McpClient()
+    {
+    }
+
     /// <summary>
     /// Gets the capabilities supported by the connected server.
     /// </summary>

src/ModelContextProtocol.Core/Client/McpClientImpl.cs

@@ -6,8 +6,10 @@
 namespace ModelContextProtocol.Client;
 
 /// <inheritdoc/>
+#pragma warning disable MCPEXP001
 internal sealed partial class McpClientImpl : McpClient
 {
+#pragma warning restore MCPEXP001
     private static Implementation DefaultImplementation { get; } = new()
     {
         Name = AssemblyNameHelper.DefaultAssemblyName.Name ?? nameof(McpClient),

src/ModelContextProtocol.Core/Server/DestinationBoundMcpServer.cs

@@ -3,7 +3,9 @@
 
 namespace ModelContextProtocol.Server;
 
+#pragma warning disable MCPEXP001
 internal sealed class DestinationBoundMcpServer(McpServerImpl server, ITransport? transport) : McpServer
+#pragma warning restore MCPEXP001
 {
     public override string? SessionId => transport?.SessionId ?? server.SessionId;
     public override string? NegotiatedProtocolVersion => server.NegotiatedProtocolVersion;

src/ModelContextProtocol.Core/Server/McpServer.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using ModelContextProtocol.Protocol;
 
 namespace ModelContextProtocol.Server;
@@ -7,6 +8,14 @@ namespace ModelContextProtocol.Server;
 /// </summary>
 public abstract partial class McpServer : McpSession
 {
+    /// <summary>
+    /// Initializes a new instance of the <see cref="McpServer"/> class.
+    /// </summary>
+    [Experimental(Experimentals.Tasks_DiagnosticId, UrlFormat = Experimentals.Tasks_Url)]
+    protected McpServer()
+    {
+    }
+
     /// <summary>
     /// Gets the capabilities supported by the client.
     /// </summary>

src/ModelContextProtocol.Core/Server/McpServerImpl.cs

@@ -9,8 +9,10 @@
 namespace ModelContextProtocol.Server;
 
 /// <inheritdoc />
+#pragma warning disable MCPEXP001
 internal sealed partial class McpServerImpl : McpServer
 {
+#pragma warning restore MCPEXP001
     internal static Implementation DefaultImplementation { get; } = new()
     {
         Name = AssemblyNameHelper.DefaultAssemblyName.Name ?? nameof(McpServer),

tests/ModelContextProtocol.Tests/Server/McpServerTests.cs

@@ -943,7 +943,9 @@ private static async Task InitializeServerAsync(TestServerTransport transport, C
         await tcs.Task.WaitAsync(TestConstants.DefaultTimeout, cancellationToken);
     }
 
+#pragma warning disable MCPEXP001
     private sealed class TestServerForIChatClient(bool supportsSampling) : McpServer
+#pragma warning restore MCPEXP001
     {
         public override ClientCapabilities? ClientCapabilities =>
             supportsSampling ? new ClientCapabilities { Sampling = new SamplingCapability() } :