using Microsoft.Extensions.Logging; using ModelContextProtocol.Protocol; using ModelContextProtocol.Server; using System.Diagnostics; using System.Diagnostics.CodeAnalysis; using System.Text.Json; using System.Text.Json.Nodes; namespace ModelContextProtocol.Client; /// /// Represents an instance of a Model Context Protocol (MCP) client session that connects to and communicates with an MCP server. /// public abstract partial class McpClient : McpSession { /// Creates an , connecting it to the specified server. /// The transport instance used to communicate with the server. /// /// A client configuration object that specifies client capabilities and protocol version. /// If , details based on the current process are used. /// /// A logger factory for creating loggers for clients. /// The to monitor for cancellation requests. The default is . /// An that's connected to the specified server. /// is . /// An error occurred while connecting to the server over HTTP. /// The server returned an error response during initialization. /// /// /// When using an HTTP-based transport (such as ), this method may throw /// if there is a problem establishing the connection to the MCP server. /// /// /// If the server requires authentication and credentials are not provided or are invalid, an /// with an HTTP 401 Unauthorized status code will be thrown. /// To authenticate with a protected server, configure the /// property of the transport with appropriate credentials before calling this method. /// /// public static async Task CreateAsync( IClientTransport clientTransport, McpClientOptions? clientOptions = null, ILoggerFactory? loggerFactory = null, CancellationToken cancellationToken = default) { Throw.IfNull(clientTransport); var transport = await clientTransport.ConnectAsync(cancellationToken).ConfigureAwait(false); var endpointName = clientTransport.Name; var clientSession = new McpClientImpl(transport, endpointName, clientOptions, loggerFactory); try { await clientSession.ConnectAsync(cancellationToken).ConfigureAwait(false); } catch (Exception ex) when (ex is not OperationCanceledException and not ClientTransportClosedException) { // ConnectAsync already disposed the session (which includes awaiting Completion). // Check if the transport provided structured completion details indicating // why the transport closed that aren't already in the original exception chain. Debug.Assert(clientSession.Completion.IsCompleted, "Completion should already be finished after ConnectAsync's DisposeAsync."); var completionDetails = await clientSession.Completion.ConfigureAwait(false); // If the transport closed with a non-graceful error (e.g., server process exited) // and the completion details carry an exception that's NOT already in the original // exception chain, throw a ClientTransportClosedException with the structured details so // callers can programmatically inspect the closure reason (exit code, stderr, etc.). // When the same exception is already in the chain (e.g., HttpRequestException from // an HTTP transport), the original exception is more appropriate to re-throw. if (completionDetails.Exception is { } detailsException && !ExceptionChainContains(ex, detailsException)) { throw new ClientTransportClosedException(completionDetails); } throw; } return clientSession; } /// /// Returns if is the same object as /// or any exception in its chain. /// private static bool ExceptionChainContains(Exception exception, Exception target) { for (Exception? current = exception; current is not null; current = current.InnerException) { if (ReferenceEquals(current, target)) { return true; } } return false; } /// /// Recreates an using an existing transport session without sending a new initialize request. /// /// The transport instance already configured to connect to the target server. /// The metadata captured from the original session that should be applied when resuming. /// Optional client settings that should mirror those used to create the original session. /// An optional logger factory for diagnostics. /// The to monitor for cancellation requests. The default is . /// An bound to the resumed session. /// , , , or is . public static async Task ResumeSessionAsync( IClientTransport clientTransport, ResumeClientSessionOptions resumeOptions, McpClientOptions? clientOptions = null, ILoggerFactory? loggerFactory = null, CancellationToken cancellationToken = default) { Throw.IfNull(clientTransport); Throw.IfNull(resumeOptions); Throw.IfNull(resumeOptions.ServerCapabilities); Throw.IfNull(resumeOptions.ServerInfo); var transport = await clientTransport.ConnectAsync(cancellationToken).ConfigureAwait(false); McpClientImpl clientSession = new(transport, clientTransport.Name, clientOptions, loggerFactory); clientSession.ResumeSession(resumeOptions); return clientSession; } /// /// Sends a ping request to verify server connectivity. /// /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A task containing the ping result. /// The server cannot be reached or returned an error response. public ValueTask PingAsync(RequestOptions? options = null, CancellationToken cancellationToken = default) { return PingAsync( new PingRequestParams { Meta = options?.GetMetaForRequest() }, cancellationToken); } /// /// Sends a ping request to verify server connectivity. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// A task containing the ping result. /// is . /// The server cannot be reached or returned an error response. public ValueTask PingAsync( PingRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return SendRequestAsync( RequestMethods.Ping, requestParams, McpJsonUtilities.JsonContext.Default.PingRequestParams, McpJsonUtilities.JsonContext.Default.PingResult, cancellationToken: cancellationToken); } /// /// Retrieves a list of available tools from the server. /// /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A list of all available tools as instances. /// The request failed or the server returned an error response. /// /// /// This overload aggregates every page into a single list and does not surface the per-result caching hints /// ( and ). To read those hints, /// use the overload, which returns the /// raw for each page. /// /// /// The SDK does not perform any internal caching of listing results; every call re-fetches all pages from the server. /// If you want to cache listing results, do so in your own code using the lower-level /// overload, which exposes the per-page /// caching hints and lets you manage pagination so each page can be cached and expired independently. /// /// public async ValueTask> ListToolsAsync( RequestOptions? options = null, CancellationToken cancellationToken = default) { ToolCacheClearing?.Invoke(); List? tools = null; ListToolsRequestParams requestParams = new() { Meta = options?.GetMetaForRequest() }; do { var toolResults = await ListToolsAsync(requestParams, cancellationToken).ConfigureAwait(false); tools ??= new(toolResults.Tools.Count); foreach (var tool in toolResults.Tools) { // Validate x-mcp-header annotations per SEP-2243. The spec requires Streamable HTTP // clients to exclude tools with invalid annotations and permits other transports // (e.g., stdio) to ignore the annotations entirely. This client validates on all // transports so a malformed definition is rejected consistently regardless of transport. if (!McpHeaderExtractor.ValidateToolSchema(tool, out var rejectionReason)) { ToolRejected?.Invoke(tool, rejectionReason!); continue; } ToolDiscovered?.Invoke(tool); tools.Add(new(this, tool, options?.JsonSerializerOptions)); } requestParams.Cursor = toolResults.NextCursor; } while (requestParams.Cursor is not null); return tools; } /// /// Invoked when a tool definition is discovered from a tools/list response. /// internal Action? ToolDiscovered; /// /// Invoked when a tool definition is rejected due to invalid x-mcp-header annotations. /// internal Action? ToolRejected; /// /// Invoked before enumerating tools to clear any previously cached tool definitions. /// internal Action? ToolCacheClearing; /// /// Retrieves a list of available tools from the server. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request as provided by the server. /// is . /// The request failed or the server returned an error response. /// /// The overload retrieves all tools by automatically handling pagination. /// This overload works with the lower-level and , returning the raw result from the server. /// Any pagination needs to be managed by the caller. /// public ValueTask ListToolsAsync( ListToolsRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return ValidateCacheableResultAsync(RequestMethods.ToolsList, SendRequestAsync( RequestMethods.ToolsList, requestParams, McpJsonUtilities.JsonContext.Default.ListToolsRequestParams, McpJsonUtilities.JsonContext.Default.ListToolsResult, cancellationToken: cancellationToken)); } /// /// Awaits a cacheable result and gives derived clients a chance to emit diagnostics (for example, a /// SEP-2549 conformance warning) before returning it. Preserves the synchronous argument validation /// performed by the callers before the request is issued. /// private async ValueTask ValidateCacheableResultAsync(string method, ValueTask resultTask) where TResult : ICacheableResult { var result = await resultTask.ConfigureAwait(false); ValidateCacheableResult(method, result); return result; } /// /// Retrieves a list of available prompts from the server. /// /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A list of all available prompts as instances. /// The request failed or the server returned an error response. /// /// /// This overload aggregates every page into a single list and does not surface the per-result caching hints /// ( and ). To read those hints, /// use the overload, which returns the /// raw for each page. /// /// /// The SDK does not perform any internal caching of listing results; every call re-fetches all pages from the server. /// If you want to cache listing results, do so in your own code using the lower-level /// overload, which exposes the per-page /// caching hints and lets you manage pagination so each page can be cached and expired independently. /// /// public async ValueTask> ListPromptsAsync( RequestOptions? options = null, CancellationToken cancellationToken = default) { List? prompts = null; ListPromptsRequestParams requestParams = new() { Meta = options?.GetMetaForRequest() }; do { var promptResults = await ListPromptsAsync(requestParams, cancellationToken).ConfigureAwait(false); prompts ??= new(promptResults.Prompts.Count); foreach (var prompt in promptResults.Prompts) { prompts.Add(new(this, prompt)); } requestParams.Cursor = promptResults.NextCursor; } while (requestParams.Cursor is not null); return prompts; } /// /// Retrieves a list of available prompts from the server. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request as provided by the server. /// is . /// The request failed or the server returned an error response. /// /// The overload retrieves all prompts by automatically handling pagination. /// This overload works with the lower-level and , returning the raw result from the server. /// Any pagination needs to be managed by the caller. /// public ValueTask ListPromptsAsync( ListPromptsRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return ValidateCacheableResultAsync(RequestMethods.PromptsList, SendRequestAsync( RequestMethods.PromptsList, requestParams, McpJsonUtilities.JsonContext.Default.ListPromptsRequestParams, McpJsonUtilities.JsonContext.Default.ListPromptsResult, cancellationToken: cancellationToken)); } /// /// Retrieves a specific prompt from the MCP server. /// /// The name of the prompt to retrieve. /// Optional arguments for the prompt. The dictionary keys are parameter names, and the values are the argument values. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A task containing the prompt's result with content and messages. /// is . /// is empty or composed entirely of whitespace. /// The request failed or the server returned an error response. public ValueTask GetPromptAsync( string name, IReadOnlyDictionary? arguments = null, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNullOrWhiteSpace(name); var serializerOptions = options?.JsonSerializerOptions ?? McpJsonUtilities.DefaultOptions; serializerOptions.MakeReadOnly(); return GetPromptAsync( new GetPromptRequestParams { Name = name, Arguments = ToArgumentsDictionary(arguments, serializerOptions), Meta = options?.GetMetaForRequest(), }, cancellationToken); } /// /// Retrieves a specific prompt from the MCP server. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request as provided by the server. /// is . /// The request failed or the server returned an error response. public ValueTask GetPromptAsync( GetPromptRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return SendRequestAsync( RequestMethods.PromptsGet, requestParams, McpJsonUtilities.JsonContext.Default.GetPromptRequestParams, McpJsonUtilities.JsonContext.Default.GetPromptResult, cancellationToken: cancellationToken); } /// /// Retrieves a list of available resource templates from the server. /// /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A list of all available resource templates as instances. /// The request failed or the server returned an error response. /// /// /// This overload aggregates every page into a single list and does not surface the per-result caching hints /// ( and ). To read those hints, /// use the overload, which returns the /// raw for each page. /// /// /// The SDK does not perform any internal caching of listing results; every call re-fetches all pages from the server. /// If you want to cache listing results, do so in your own code using the lower-level /// overload, which exposes the per-page /// caching hints and lets you manage pagination so each page can be cached and expired independently. /// /// public async ValueTask> ListResourceTemplatesAsync( RequestOptions? options = null, CancellationToken cancellationToken = default) { List? resourceTemplates = null; ListResourceTemplatesRequestParams requestParams = new() { Meta = options?.GetMetaForRequest() }; do { var templateResults = await ListResourceTemplatesAsync(requestParams, cancellationToken).ConfigureAwait(false); resourceTemplates ??= new(templateResults.ResourceTemplates.Count); foreach (var template in templateResults.ResourceTemplates) { resourceTemplates.Add(new(this, template)); } requestParams.Cursor = templateResults.NextCursor; } while (requestParams.Cursor is not null); return resourceTemplates; } /// /// Retrieves a list of available resource templates from the server. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request as provided by the server. /// is . /// The request failed or the server returned an error response. /// /// The overload retrieves all resource templates by automatically handling pagination. /// This overload works with the lower-level and , returning the raw result from the server. /// Any pagination needs to be managed by the caller. /// public ValueTask ListResourceTemplatesAsync( ListResourceTemplatesRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return ValidateCacheableResultAsync(RequestMethods.ResourcesTemplatesList, SendRequestAsync( RequestMethods.ResourcesTemplatesList, requestParams, McpJsonUtilities.JsonContext.Default.ListResourceTemplatesRequestParams, McpJsonUtilities.JsonContext.Default.ListResourceTemplatesResult, cancellationToken: cancellationToken)); } /// /// Retrieves a list of available resources from the server. /// /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A list of all available resources as instances. /// The request failed or the server returned an error response. /// /// /// This overload aggregates every page into a single list and does not surface the per-result caching hints /// ( and ). To read those hints, /// use the overload, which returns the /// raw for each page. /// /// /// The SDK does not perform any internal caching of listing results; every call re-fetches all pages from the server. /// If you want to cache listing results, do so in your own code using the lower-level /// overload, which exposes the per-page /// caching hints and lets you manage pagination so each page can be cached and expired independently. /// /// public async ValueTask> ListResourcesAsync( RequestOptions? options = null, CancellationToken cancellationToken = default) { List? resources = null; ListResourcesRequestParams requestParams = new() { Meta = options?.GetMetaForRequest() }; do { var resourceResults = await ListResourcesAsync(requestParams, cancellationToken).ConfigureAwait(false); resources ??= new(resourceResults.Resources.Count); foreach (var resource in resourceResults.Resources) { resources.Add(new(this, resource)); } requestParams.Cursor = resourceResults.NextCursor; } while (requestParams.Cursor is not null); return resources; } /// /// Retrieves a list of available resources from the server. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request as provided by the server. /// is . /// The request failed or the server returned an error response. /// /// The overload retrieves all resources by automatically handling pagination. /// This overload works with the lower-level and , returning the raw result from the server. /// Any pagination needs to be managed by the caller. /// public ValueTask ListResourcesAsync( ListResourcesRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return ValidateCacheableResultAsync(RequestMethods.ResourcesList, SendRequestAsync( RequestMethods.ResourcesList, requestParams, McpJsonUtilities.JsonContext.Default.ListResourcesRequestParams, McpJsonUtilities.JsonContext.Default.ListResourcesResult, cancellationToken: cancellationToken)); } /// /// Reads a resource from the server. /// /// The URI of the resource. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// is . /// The request failed or the server returned an error response. public ValueTask ReadResourceAsync( Uri uri, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNull(uri); return ReadResourceAsync(uri.AbsoluteUri, options, cancellationToken); } /// /// Reads a resource from the server. /// /// The URI of the resource. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// is . /// is empty or composed entirely of whitespace. /// The request failed or the server returned an error response. public ValueTask ReadResourceAsync( string uri, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNullOrWhiteSpace(uri); return ReadResourceAsync(new ReadResourceRequestParams { Uri = uri, Meta = options?.GetMetaForRequest(), }, cancellationToken); } /// /// Reads a resource from the server. /// /// The URI template of the resource. /// Arguments to use to format . /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// or is . /// is empty or composed entirely of whitespace. /// The request failed or the server returned an error response. public ValueTask ReadResourceAsync( string uriTemplate, IReadOnlyDictionary arguments, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNullOrWhiteSpace(uriTemplate); Throw.IfNull(arguments); return ReadResourceAsync( new ReadResourceRequestParams { Uri = UriTemplate.FormatUri(uriTemplate, arguments), Meta = options?.GetMetaForRequest(), }, cancellationToken); } /// /// Reads a resource from the server. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request. /// is . /// The request failed or the server returned an error response. public ValueTask ReadResourceAsync( ReadResourceRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return ValidateCacheableResultAsync(RequestMethods.ResourcesRead, SendRequestAsync( RequestMethods.ResourcesRead, requestParams, McpJsonUtilities.JsonContext.Default.ReadResourceRequestParams, McpJsonUtilities.JsonContext.Default.ReadResourceResult, cancellationToken: cancellationToken)); } /// /// Requests completion suggestions for a prompt argument or resource reference. /// /// The reference object specifying the type and optional URI or name. /// The name of the argument for which completions are requested. /// The current value of the argument, used to filter relevant completions. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A containing completion suggestions. /// or is . /// is empty or composed entirely of whitespace. /// The request failed or the server returned an error response. public ValueTask CompleteAsync( Reference reference, string argumentName, string argumentValue, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNull(reference); Throw.IfNullOrWhiteSpace(argumentName); return CompleteAsync( new CompleteRequestParams { Ref = reference, Argument = new() { Name = argumentName, Value = argumentValue }, Meta = options?.GetMetaForRequest(), }, cancellationToken); } /// /// Requests completion suggestions for a prompt argument or resource reference. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request. /// is . /// The request failed or the server returned an error response. public ValueTask CompleteAsync( CompleteRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return SendRequestAsync( RequestMethods.CompletionComplete, requestParams, McpJsonUtilities.JsonContext.Default.CompleteRequestParams, McpJsonUtilities.JsonContext.Default.CompleteResult, cancellationToken: cancellationToken); } /// /// Subscribes to a resource on the server to receive notifications when it changes. /// /// The URI of the resource to subscribe to. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A task that represents the asynchronous operation. /// is . /// The request failed or the server returned an error response. public Task SubscribeToResourceAsync(Uri uri, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNull(uri); return SubscribeToResourceAsync(uri.AbsoluteUri, options, cancellationToken); } /// /// Subscribes to a resource on the server to receive notifications when it changes. /// /// The URI of the resource to which to subscribe. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A task that represents the asynchronous operation. /// is . /// is empty or composed entirely of whitespace. /// The request failed or the server returned an error response. public Task SubscribeToResourceAsync(string uri, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNullOrWhiteSpace(uri); return SubscribeToResourceAsync( new SubscribeRequestParams { Uri = uri, Meta = options?.GetMetaForRequest(), }, cancellationToken); } /// /// Subscribes to a resource on the server to receive notifications when it changes. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request. /// is . /// The request failed or the server returned an error response. /// /// /// This method subscribes to resource update notifications but does not register a handler. /// To receive notifications, you must separately call /// with and filter for the specific resource URI. /// To unsubscribe, call and dispose the handler registration. /// /// /// For a simpler API that handles both subscription and notification registration in a single call, /// use . /// /// /// The 2026-07-28 protocol revision (SEP-2575) removed resources/subscribe in favor of /// with resourceSubscriptions. On a session that /// negotiated that revision or later, this method throws an with /// . /// /// public Task SubscribeToResourceAsync( SubscribeRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return SendRequestAsync( RequestMethods.ResourcesSubscribe, requestParams, McpJsonUtilities.JsonContext.Default.SubscribeRequestParams, McpJsonUtilities.JsonContext.Default.EmptyResult, cancellationToken: cancellationToken).AsTask(); } /// /// Subscribes to a resource on the server and registers a handler for notifications when it changes. /// /// The URI of the resource to which to subscribe. /// The handler to invoke when the resource is updated. It receives for the subscribed resource. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// /// A task that completes with an that, when disposed, unsubscribes from the resource /// and removes the notification handler. /// /// or is . /// The request failed or the server returned an error response. /// /// /// This method provides a convenient way to subscribe to resource updates and handle notifications in a single call. /// The returned manages both the subscription and the notification handler registration. /// When disposed, it automatically unsubscribes from the resource and removes the handler. /// /// /// The handler will only be invoked for notifications related to the specified resource URI. /// Notifications for other resources are filtered out automatically. /// /// public Task SubscribeToResourceAsync( Uri uri, Func handler, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNull(uri); return SubscribeToResourceAsync(uri.AbsoluteUri, handler, options, cancellationToken); } /// /// Subscribes to a resource on the server and registers a handler for notifications when it changes. /// /// The URI of the resource to which to subscribe. /// The handler to invoke when the resource is updated. It receives for the subscribed resource. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// /// A task that completes with an that, when disposed, unsubscribes from the resource /// and removes the notification handler. /// /// or is . /// is empty or composed entirely of whitespace. /// The request failed or the server returned an error response. /// /// /// This method provides a convenient way to subscribe to resource updates and handle notifications in a single call. /// The returned manages both the subscription and the notification handler registration. /// When disposed, it automatically unsubscribes from the resource and removes the handler. /// /// /// The handler will only be invoked for notifications related to the specified resource URI. /// Notifications for other resources are filtered out automatically. /// /// public async Task SubscribeToResourceAsync( string uri, Func handler, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNullOrWhiteSpace(uri); Throw.IfNull(handler); // Register a notification handler that filters for this specific resource IAsyncDisposable handlerRegistration = RegisterNotificationHandler( NotificationMethods.ResourceUpdatedNotification, async (notification, ct) => { if (JsonSerializer.Deserialize(notification.Params, McpJsonUtilities.JsonContext.Default.ResourceUpdatedNotificationParams) is { } resourceUpdate && UriTemplate.UriTemplateComparer.Instance.Equals(resourceUpdate.Uri, uri)) { await handler(resourceUpdate, ct).ConfigureAwait(false); } }); try { // Subscribe to the resource await SubscribeToResourceAsync(uri, options, cancellationToken).ConfigureAwait(false); } catch { // If subscription fails, unregister the handler before propagating the exception await handlerRegistration.DisposeAsync().ConfigureAwait(false); throw; } // Return a disposable that unsubscribes and removes the handler return new ResourceSubscription(this, uri, handlerRegistration, options); } /// /// Manages a resource subscription, handling both unsubscription and handler disposal. /// private sealed class ResourceSubscription : IAsyncDisposable { private readonly McpClient _client; private readonly string _uri; private readonly IAsyncDisposable _handlerRegistration; private readonly RequestOptions? _options; private int _disposed; public ResourceSubscription(McpClient client, string uri, IAsyncDisposable handlerRegistration, RequestOptions? options) { _client = client; _uri = uri; _handlerRegistration = handlerRegistration; _options = options; } public async ValueTask DisposeAsync() { if (Interlocked.Exchange(ref _disposed, 1) != 0) { return; } try { // Unsubscribe from the resource await _client.UnsubscribeFromResourceAsync(_uri, _options, CancellationToken.None).ConfigureAwait(false); } finally { // Dispose the notification handler registration await _handlerRegistration.DisposeAsync().ConfigureAwait(false); } } } /// /// Unsubscribes from a resource on the server to stop receiving notifications about its changes. /// /// The URI of the resource to unsubscribe from. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A task that represents the asynchronous operation. /// is . /// The request failed or the server returned an error response. public Task UnsubscribeFromResourceAsync(Uri uri, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNull(uri); return UnsubscribeFromResourceAsync(uri.AbsoluteUri, options, cancellationToken); } /// /// Unsubscribes from a resource on the server to stop receiving notifications about its changes. /// /// The URI of the resource to unsubscribe from. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A task that represents the asynchronous operation. /// is . /// is empty or composed entirely of whitespace. /// The request failed or the server returned an error response. public Task UnsubscribeFromResourceAsync(string uri, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNullOrWhiteSpace(uri); return UnsubscribeFromResourceAsync( new UnsubscribeRequestParams { Uri = uri, Meta = options?.GetMetaForRequest() }, cancellationToken); } /// /// Unsubscribes from a resource on the server to stop receiving notifications about its changes. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request. /// is . /// The request failed or the server returned an error response. /// /// The 2026-07-28 protocol revision (SEP-2575) removed resources/unsubscribe in favor of /// with resourceSubscriptions. On a session that /// negotiated that revision or later, this method throws an with /// . /// public Task UnsubscribeFromResourceAsync( UnsubscribeRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return SendRequestAsync( RequestMethods.ResourcesUnsubscribe, requestParams, McpJsonUtilities.JsonContext.Default.UnsubscribeRequestParams, McpJsonUtilities.JsonContext.Default.EmptyResult, cancellationToken: cancellationToken).AsTask(); } /// /// Invokes a tool on the server. /// /// The name of the tool to invoke. /// An optional dictionary of arguments to pass to the tool. /// An optional progress handler for tracking operation progress. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// The result of the tool invocation. /// is . /// The request failed or the server returned an error response. public ValueTask CallToolAsync( string toolName, IReadOnlyDictionary? arguments = null, IProgress? progress = null, RequestOptions? options = null, CancellationToken cancellationToken = default) { Throw.IfNull(toolName); var serializerOptions = options?.JsonSerializerOptions ?? McpJsonUtilities.DefaultOptions; serializerOptions.MakeReadOnly(); if (progress is null) { return CallToolAsync( new CallToolRequestParams { Name = toolName, Arguments = ToArgumentsDictionary(arguments, serializerOptions), Meta = options?.GetMetaForRequest(), }, cancellationToken); } return SendRequestWithProgressAsync(toolName, arguments, progress, options?.GetMetaForRequest(), serializerOptions, cancellationToken); async ValueTask SendRequestWithProgressAsync( string toolName, IReadOnlyDictionary? arguments, IProgress progress, JsonObject? meta, JsonSerializerOptions serializerOptions, CancellationToken cancellationToken) { ProgressToken progressToken = new(Guid.NewGuid().ToString("N")); await using var _ = RegisterNotificationHandler(NotificationMethods.ProgressNotification, (notification, cancellationToken) => { if (JsonSerializer.Deserialize(notification.Params, McpJsonUtilities.JsonContext.Default.ProgressNotificationParams) is { } pn && pn.ProgressToken == progressToken) { progress.Report(pn.Progress); } return default; }).ConfigureAwait(false); JsonObject metaWithProgress = meta is not null ? (JsonObject)meta.DeepClone() : []; metaWithProgress["progressToken"] = progressToken.ToString(); return await CallToolAsync( new() { Name = toolName, Arguments = ToArgumentsDictionary(arguments, serializerOptions), Meta = metaWithProgress, }, cancellationToken).ConfigureAwait(false); } } /// /// Invokes a tool on the server. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request. /// is . /// The request failed or the server returned an error response. public ValueTask CallToolAsync( CallToolRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return SendRequestAsync( RequestMethods.ToolsCall, requestParams, McpJsonUtilities.JsonContext.Default.CallToolRequestParams, McpJsonUtilities.JsonContext.Default.CallToolResult, cancellationToken: cancellationToken); } /// /// Sets the logging level for the server to control which log messages are sent to the client. /// /// The minimum severity level of log messages to receive from the server. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A task representing the asynchronous operation. /// The request failed or the server returned an error response. [Obsolete(Obsoletions.DeprecatedLogging_Message, DiagnosticId = Obsoletions.Deprecated_DiagnosticId, UrlFormat = Obsoletions.Deprecated_Url)] public Task SetLoggingLevelAsync(LogLevel level, RequestOptions? options = null, CancellationToken cancellationToken = default) => SetLoggingLevelAsync(McpServerImpl.ToLoggingLevel(level), options, cancellationToken); /// /// Sets the logging level for the server to control which log messages are sent to the client. /// /// The minimum severity level of log messages to receive from the server. /// Optional request options including metadata, serialization settings, and progress tracking. /// The to monitor for cancellation requests. The default is . /// A task representing the asynchronous operation. /// The request failed or the server returned an error response. [Obsolete(Obsoletions.DeprecatedLogging_Message, DiagnosticId = Obsoletions.Deprecated_DiagnosticId, UrlFormat = Obsoletions.Deprecated_Url)] public Task SetLoggingLevelAsync(LoggingLevel level, RequestOptions? options = null, CancellationToken cancellationToken = default) { return SetLoggingLevelAsync( new SetLevelRequestParams { Level = level, Meta = options?.GetMetaForRequest() }, cancellationToken); } /// /// Sets the logging level for the server to control which log messages are sent to the client. /// /// The request parameters to send in the request. /// The to monitor for cancellation requests. The default is . /// The result of the request. /// is . /// The request failed or the server returned an error response. [Obsolete(Obsoletions.DeprecatedLogging_Message, DiagnosticId = Obsoletions.Deprecated_DiagnosticId, UrlFormat = Obsoletions.Deprecated_Url)] public Task SetLoggingLevelAsync( SetLevelRequestParams requestParams, CancellationToken cancellationToken = default) { Throw.IfNull(requestParams); return SendRequestAsync( RequestMethods.LoggingSetLevel, requestParams, McpJsonUtilities.JsonContext.Default.SetLevelRequestParams, McpJsonUtilities.JsonContext.Default.EmptyResult, cancellationToken: cancellationToken).AsTask(); } private static Dictionary? ToArgumentsDictionary( IReadOnlyDictionary? arguments, JsonSerializerOptions options) { var typeInfo = options.GetTypeInfo(); Dictionary? result = null; if (arguments is not null) { result = new(arguments.Count); foreach (var kvp in arguments) { result.Add(kvp.Key, kvp.Value is JsonElement je ? je : JsonSerializer.SerializeToElement(kvp.Value, typeInfo)); } } return result; } }