Add initial Activity / Metric support

Directory.Packages.props

@@ -33,6 +33,8 @@
     <PackageVersion Include="Microsoft.Extensions.Logging.Console" Version="$(MicrosoftExtensionsVersion)" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageVersion Include="Moq" Version="4.20.72" />
+    <PackageVersion Include="OpenTelemetry" Version="1.11.2" />
+    <PackageVersion Include="OpenTelemetry.Exporter.InMemory" Version="1.11.2" />
     <PackageVersion Include="Serilog.Extensions.Hosting" Version="9.0.0" />
     <PackageVersion Include="Serilog.Extensions.Logging" Version="9.0.0" />
     <PackageVersion Include="Serilog.Sinks.Console" Version="6.0.0" />

src/ModelContextProtocol/Diagnostics.cs

@@ -0,0 +1,29 @@
+using System.Diagnostics;
+using System.Diagnostics.Metrics;
+
+namespace ModelContextProtocol;
+
+internal static class Diagnostics
+{
+    internal static ActivitySource ActivitySource { get; } = new("ModelContextProtocol");
+
+    /// <summary>
+    /// Follows boundaries from http.server.request.duration/http.client.request.duration
+    /// </summary>
+    internal static InstrumentAdvice<double> ShortSecondsBucketBoundaries { get; } = new()
+    {
+        HistogramBucketBoundaries = [0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10],
+    };
+
+    /// <summary>
+    /// Not based on a standard. Larger bucket sizes for longer lasting operations, e.g. HTTP connection duration.
+    /// See https://github.com/open-telemetry/semantic-conventions/issues/336
+    /// </summary>
+    internal static InstrumentAdvice<double> LongSecondsBucketBoundaries { get; } = new()
+    {
+        HistogramBucketBoundaries = [0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 30, 60, 120, 300],
+    };
+
+    internal static Meter Meter { get; } = new("ModelContextProtocol");
+
+}

src/ModelContextProtocol/Protocol/Messages/RequestId.cs

@@ -34,9 +34,13 @@ public RequestId(long value)
     /// <summary>Gets whether the identifier is uninitialized.</summary>
     public bool IsDefault => _id is null;
 
+    /// <summary>Gets the underlying object for this id.</summary>
+    /// <remarks>This will either be a <see cref="string"/>, a boxed <see cref="long"/>, or <see langword="null"/>.</remarks>
+    public object? Id => _id;
+
     /// <inheritdoc />
     public override string ToString() =>
-        _id is string stringValue ? $"\"{stringValue}\"" :
+        _id is string stringValue ? stringValue :
         _id is long longValue ? longValue.ToString(CultureInfo.InvariantCulture) :
         string.Empty;
 

src/ModelContextProtocol/Shared/McpJsonRpcEndpoint.cs

@@ -3,6 +3,7 @@
 using ModelContextProtocol.Logging;
 using ModelContextProtocol.Protocol.Messages;
 using ModelContextProtocol.Protocol.Transport;
+using ModelContextProtocol.Server;
 using ModelContextProtocol.Utils;
 using System.Diagnostics.CodeAnalysis;
 
@@ -63,7 +64,7 @@ public Task SendMessageAsync(IJsonRpcMessage message, CancellationToken cancella
     protected void StartSession(ITransport sessionTransport)
     {
         _sessionCts = new CancellationTokenSource();
-        _session = new McpSession(sessionTransport, EndpointName, _requestHandlers, _notificationHandlers, _logger);
+        _session = new McpSession(this is IMcpServer, sessionTransport, EndpointName, _requestHandlers, _notificationHandlers, _logger);
         MessageProcessingTask = _session.ProcessMessagesAsync(_sessionCts.Token);
     }