Remove obsolete APIs from codebase

src/ModelContextProtocol.Core/Client/McpClientImpl.cs

@@ -58,12 +58,10 @@ private void RegisterHandlers(McpClientOptions options, NotificationHandlers not
     {
         McpClientHandlers handlers = options.Handlers;
 
-#pragma warning disable CS0618 // Type or member is obsolete
-        var notificationHandlersFromOptions = handlers.NotificationHandlers ?? options.Capabilities?.NotificationHandlers;
-        var samplingHandler = handlers.SamplingHandler ?? options.Capabilities?.Sampling?.SamplingHandler;
-        var rootsHandler = handlers.RootsHandler ?? options.Capabilities?.Roots?.RootsHandler;
-        var elicitationHandler = handlers.ElicitationHandler ?? options.Capabilities?.Elicitation?.ElicitationHandler;
-#pragma warning restore CS0618 // Type or member is obsolete
+        var notificationHandlersFromOptions = handlers.NotificationHandlers;
+        var samplingHandler = handlers.SamplingHandler;
+        var rootsHandler = handlers.RootsHandler;
+        var elicitationHandler = handlers.ElicitationHandler;
 
         if (notificationHandlersFromOptions is not null)
         {

src/ModelContextProtocol.Core/IMcpEndpoint.cs

@@ -67,9 +67,8 @@ public interface IMcpEndpoint : IAsyncDisposable
     /// <remarks>
     /// <para>
     /// This method provides low-level access to send any JSON-RPC message. For specific message types,
-    /// consider using the higher-level methods such as <see cref="SendRequestAsync"/> or extension methods
-    /// like <see cref="McpEndpointExtensions.SendNotificationAsync(IMcpEndpoint, string, CancellationToken)"/>,
-    /// which provide a simpler API.
+    /// consider using the higher-level methods such as <see cref="SendRequestAsync"/> or
+    /// <see cref="McpSession.SendNotificationAsync"/>, which provide a simpler API.
     /// </para>
     /// <para>
     /// The method will serialize the message and transmit it using the underlying transport mechanism.

src/ModelContextProtocol.Core/McpEndpointExtensions.cs

@@ -23,130 +23,4 @@ namespace ModelContextProtocol;
 /// </remarks>
 public static class McpEndpointExtensions
 {
-    /// <summary>
-    /// Sends a JSON-RPC request and attempts to deserialize the result to <typeparamref name="TResult"/>.
-    /// </summary>
-    /// <typeparam name="TParameters">The type of the request parameters to serialize from.</typeparam>
-    /// <typeparam name="TResult">The type of the result to deserialize to.</typeparam>
-    /// <param name="endpoint">The MCP client or server instance.</param>
-    /// <param name="method">The JSON-RPC method name to invoke.</param>
-    /// <param name="parameters">Object representing the request parameters.</param>
-    /// <param name="requestId">The request id for the request.</param>
-    /// <param name="serializerOptions">The options governing request serialization.</param>
-    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
-    /// <returns>A task that represents the asynchronous operation. The task result contains the deserialized result.</returns>
-    [Obsolete($"Use {nameof(McpSession)}.{nameof(McpSession.SendRequestAsync)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public static ValueTask<TResult> SendRequestAsync<TParameters, TResult>(
-        this IMcpEndpoint endpoint,
-        string method,
-        TParameters parameters,
-        JsonSerializerOptions? serializerOptions = null,
-        RequestId requestId = default,
-        CancellationToken cancellationToken = default)
-        where TResult : notnull
-        => AsSessionOrThrow(endpoint).SendRequestAsync<TParameters, TResult>(method, parameters, serializerOptions, requestId, cancellationToken);
-
-    /// <summary>
-    /// Sends a parameterless notification to the connected endpoint.
-    /// </summary>
-    /// <param name="client">The MCP client or server instance.</param>
-    /// <param name="method">The notification method name.</param>
-    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
-    /// <returns>A task that represents the asynchronous send operation.</returns>
-    /// <remarks>
-    /// <para>
-    /// This method sends a notification without any parameters. Notifications are one-way messages 
-    /// that don't expect a response. They are commonly used for events, status updates, or to signal 
-    /// changes in state.
-    /// </para>
-    /// </remarks>
-    [Obsolete($"Use {nameof(McpSession)}.{nameof(McpSession.SendNotificationAsync)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public static Task SendNotificationAsync(this IMcpEndpoint client, string method, CancellationToken cancellationToken = default)
-        => AsSessionOrThrow(client).SendNotificationAsync(method, cancellationToken);
-
-    /// <summary>
-    /// Sends a notification with parameters to the connected endpoint.
-    /// </summary>
-    /// <typeparam name="TParameters">The type of the notification parameters to serialize.</typeparam>
-    /// <param name="endpoint">The MCP client or server instance.</param>
-    /// <param name="method">The JSON-RPC method name for the notification.</param>
-    /// <param name="parameters">Object representing the notification parameters.</param>
-    /// <param name="serializerOptions">The options governing parameter serialization. If null, default options are used.</param>
-    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
-    /// <returns>A task that represents the asynchronous send operation.</returns>
-    /// <remarks>
-    /// <para>
-    /// This method sends a notification with parameters to the connected endpoint. Notifications are one-way 
-    /// messages that don't expect a response, commonly used for events, status updates, or signaling changes.
-    /// </para>
-    /// <para>
-    /// The parameters object is serialized to JSON according to the provided serializer options or the default 
-    /// options if none are specified.
-    /// </para>
-    /// <para>
-    /// The Model Context Protocol defines several standard notification methods in <see cref="NotificationMethods"/>,
-    /// but custom methods can also be used for application-specific notifications.
-    /// </para>
-    /// </remarks>
-    [Obsolete($"Use {nameof(McpSession)}.{nameof(McpSession.SendNotificationAsync)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public static Task SendNotificationAsync<TParameters>(
-        this IMcpEndpoint endpoint,
-        string method,
-        TParameters parameters,
-        JsonSerializerOptions? serializerOptions = null,
-        CancellationToken cancellationToken = default)
-        => AsSessionOrThrow(endpoint).SendNotificationAsync(method, parameters, serializerOptions, cancellationToken);
-
-    /// <summary>
-    /// Notifies the connected endpoint of progress for a long-running operation.
-    /// </summary>
-    /// <param name="endpoint">The endpoint issuing the notification.</param>
-    /// <param name="progressToken">The <see cref="ProgressToken"/> identifying the operation for which progress is being reported.</param>
-    /// <param name="progress">The progress update to send, containing information such as percentage complete or status message.</param>
-    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
-    /// <returns>A task representing the completion of the notification operation (not the operation being tracked).</returns>
-    /// <exception cref="ArgumentNullException"><paramref name="endpoint"/> is <see langword="null"/>.</exception>
-    /// <remarks>
-    /// <para>
-    /// This method sends a progress notification to the connected endpoint using the Model Context Protocol's
-    /// standardized progress notification format. Progress updates are identified by a <see cref="ProgressToken"/>
-    /// that allows the recipient to correlate multiple updates with a specific long-running operation.
-    /// </para>
-    /// <para>
-    /// Progress notifications are sent asynchronously and don't block the operation from continuing.
-    /// </para>
-    /// </remarks>
-    [Obsolete($"Use {nameof(McpSession)}.{nameof(McpSession.NotifyProgressAsync)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public static Task NotifyProgressAsync(
-        this IMcpEndpoint endpoint,
-        ProgressToken progressToken,
-        ProgressNotificationValue progress,
-        CancellationToken cancellationToken = default)
-        => AsSessionOrThrow(endpoint).NotifyProgressAsync(progressToken, progress, cancellationToken);
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-#pragma warning disable CS0618 // Type or member is obsolete
-    private static McpSession AsSessionOrThrow(IMcpEndpoint endpoint, [CallerMemberName] string memberName = "")
-#pragma warning restore CS0618 // Type or member is obsolete
-    {
-        if (endpoint is not McpSession session)
-        {
-            ThrowInvalidEndpointType(memberName);
-        }
-
-        return session;
-
-        [DoesNotReturn]
-        [MethodImpl(MethodImplOptions.NoInlining)]
-        static void ThrowInvalidEndpointType(string memberName)
-            => throw new InvalidOperationException(
-                $"Only arguments assignable to '{nameof(McpSession)}' are supported. " +
-                $"Prefer using '{nameof(McpServer)}.{memberName}' instead, as " +
-                $"'{nameof(McpEndpointExtensions)}.{memberName}' is obsolete and will be " +
-                $"removed in the future.");
-    }
 }

src/ModelContextProtocol.Core/Protocol/ClientCapabilities.cs

@@ -67,25 +67,4 @@ public sealed class ClientCapabilities
     [JsonPropertyName("elicitation")]
     public ElicitationCapability? Elicitation { get; set; }
 
-    /// <summary>Gets or sets notification handlers to register with the client.</summary>
-    /// <remarks>
-    /// <para>
-    /// When constructed, the client will enumerate these handlers once, which may contain multiple handlers per notification method key.
-    /// The client will not re-enumerate the sequence after initialization.
-    /// </para>
-    /// <para>
-    /// Notification handlers allow the client to respond to server-sent notifications for specific methods.
-    /// Each key in the collection is a notification method name, and each value is a callback that will be invoked
-    /// when a notification with that method is received.
-    /// </para>
-    /// <para>
-    /// Handlers provided via <see cref="NotificationHandlers"/> will be registered with the client for the lifetime of the client.
-    /// For transient handlers, <see cref="McpSession.RegisterNotificationHandler"/> may be used to register a handler that can
-    /// then be unregistered by disposing of the <see cref="IAsyncDisposable"/> returned from the method.
-    /// </para>
-    /// </remarks>
-    [JsonIgnore]
-    [Obsolete($"Use {nameof(McpClientOptions.Handlers.NotificationHandlers)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public IEnumerable<KeyValuePair<string, Func<JsonRpcNotification, CancellationToken, ValueTask>>>? NotificationHandlers { get; set; }
 }

src/ModelContextProtocol.Core/Protocol/CompletionsCapability.cs

@@ -28,16 +28,4 @@ namespace ModelContextProtocol.Protocol;
 /// </remarks>
 public sealed class CompletionsCapability
 {
-    /// <summary>
-    /// Gets or sets the handler for completion requests.
-    /// </summary>
-    /// <remarks>
-    /// This handler provides auto-completion suggestions for prompt arguments or resource references in the Model Context Protocol.
-    /// The handler receives a reference type (e.g., "ref/prompt" or "ref/resource") and the current argument value,
-    /// and should return appropriate completion suggestions.
-    /// </remarks>
-    [JsonIgnore]
-    [Obsolete($"Use {nameof(McpServerOptions.Handlers.CompleteHandler)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public McpRequestHandler<CompleteRequestParams, CompleteResult>? CompleteHandler { get; set; }
 }

src/ModelContextProtocol.Core/Protocol/ElicitationCapability.cs

@@ -23,21 +23,4 @@ namespace ModelContextProtocol.Protocol;
 /// </remarks>
 public sealed class ElicitationCapability
 {
-    /// <summary>
-    /// Gets or sets the handler for processing <see cref="RequestMethods.ElicitationCreate"/> requests.
-    /// </summary>
-    /// <remarks>
-    /// <para>
-    /// This handler function is called when an MCP server requests the client to provide additional
-    /// information during interactions. The client must set this property for the elicitation capability to work.
-    /// </para>
-    /// <para>
-    /// The handler receives message parameters and a cancellation token.
-    /// It should return a <see cref="ElicitResult"/> containing the response to the elicitation request.
-    /// </para>
-    /// </remarks>
-    [JsonIgnore]
-    [Obsolete($"Use {nameof(McpClientOptions.Handlers.ElicitationHandler)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public Func<ElicitRequestParams?, CancellationToken, ValueTask<ElicitResult>>? ElicitationHandler { get; set; }
 }

src/ModelContextProtocol.Core/Protocol/LoggingCapability.cs

@@ -20,11 +20,4 @@ namespace ModelContextProtocol.Protocol;
 /// </remarks>
 public sealed class LoggingCapability
 {
-    /// <summary>
-    /// Gets or sets the handler for set logging level requests from clients.
-    /// </summary>
-    [JsonIgnore]
-    [Obsolete($"Use {nameof(McpServerOptions.Handlers.SetLoggingLevelHandler)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public McpRequestHandler<SetLevelRequestParams, EmptyResult>? SetLoggingLevelHandler { get; set; }
 }

src/ModelContextProtocol.Core/Protocol/PromptsCapability.cs

@@ -32,58 +32,4 @@ public sealed class PromptsCapability
     [JsonPropertyName("listChanged")]
     public bool? ListChanged { get; set; }
 
-    /// <summary>
-    /// Gets or sets the handler for <see cref="RequestMethods.PromptsList"/> requests.
-    /// </summary>
-    /// <remarks>
-    /// This handler is invoked when a client requests a list of available prompts from the server
-    /// via a <see cref="RequestMethods.PromptsList"/> request. Results from this handler are returned
-    /// along with any prompts defined in <see cref="PromptCollection"/>.
-    /// </remarks>
-    [JsonIgnore]
-    [Obsolete($"Use {nameof(McpServerOptions.Handlers.ListPromptsHandler)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public McpRequestHandler<ListPromptsRequestParams, ListPromptsResult>? ListPromptsHandler { get; set; }
-
-    /// <summary>
-    /// Gets or sets the handler for <see cref="RequestMethods.PromptsGet"/> requests.
-    /// </summary>
-    /// <remarks>
-    /// <para>
-    /// This handler is invoked when a client requests details for a specific prompt by name and provides arguments
-    /// for the prompt if needed. The handler receives the request context containing the prompt name and any arguments,
-    /// and should return a <see cref="GetPromptResult"/> with the prompt messages and other details.
-    /// </para>
-    /// <para>
-    /// This handler will be invoked if the requested prompt name is not found in the <see cref="PromptCollection"/>,
-    /// allowing for dynamic prompt generation or retrieval from external sources.
-    /// </para>
-    /// </remarks>
-    [JsonIgnore]
-    [Obsolete($"Use {nameof(McpServerOptions.Handlers.GetPromptHandler)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public McpRequestHandler<GetPromptRequestParams, GetPromptResult>? GetPromptHandler { get; set; }
-
-    /// <summary>
-    /// Gets or sets a collection of prompts that will be served by the server.
-    /// </summary>
-    /// <remarks>
-    /// <para>
-    /// The <see cref="PromptCollection"/> contains the predefined prompts that clients can request from the server.
-    /// This collection works in conjunction with <see cref="ListPromptsHandler"/> and <see cref="GetPromptHandler"/>
-    /// when those are provided:
-    /// </para>
-    /// <para>
-    /// - For <see cref="RequestMethods.PromptsList"/> requests: The server returns all prompts from this collection
-    ///   plus any additional prompts provided by the <see cref="ListPromptsHandler"/> if it's set.
-    /// </para>
-    /// <para>
-    /// - For <see cref="RequestMethods.PromptsGet"/> requests: The server first checks this collection for the requested prompt.
-    ///   If not found, it will invoke the <see cref="GetPromptHandler"/> as a fallback if one is set.
-    /// </para>
-    /// </remarks>
-    [JsonIgnore]
-    [Obsolete($"Use {nameof(McpServerOptions.PromptCollection)} instead. This member will be removed in a subsequent release.")] // See: https://github.com/modelcontextprotocol/csharp-sdk/issues/774
-    [EditorBrowsable(EditorBrowsableState.Never)]
-    public McpServerPrimitiveCollection<McpServerPrompt>? PromptCollection { get; set; }
 }