Add ModelContextProtocol.Core package (#428)

src/ModelContextProtocol.Core/Protocol/LoggingLevel.cs

@@ -0,0 +1,45 @@
+using System.Text.Json.Serialization;
+
+namespace ModelContextProtocol.Protocol;
+
+/// <summary>
+/// Indicates the severity of a log message.
+/// </summary>
+/// <remarks>
+/// These map to syslog message severities, as specified in <see href="https://datatracker.ietf.org/doc/html/rfc5424#section-6.2.1">RFC-5424</see>.
+/// </remarks>
+[JsonConverter(typeof(CustomizableJsonStringEnumConverter<LoggingLevel>))]
+public enum LoggingLevel
+{
+    /// <summary>Detailed debug information, typically only valuable to developers.</summary>
+    [JsonStringEnumMemberName("debug")]
+    Debug,
+
+    /// <summary>Normal operational messages that require no action.</summary>
+    [JsonStringEnumMemberName("info")]
+    Info,
+
+    /// <summary>Normal but significant events that might deserve attention.</summary>
+    [JsonStringEnumMemberName("notice")]
+    Notice,
+
+    /// <summary>Warning conditions that don't represent an error but indicate potential issues.</summary>
+    [JsonStringEnumMemberName("warning")]
+    Warning,
+
+    /// <summary>Error conditions that should be addressed but don't require immediate action.</summary>
+    [JsonStringEnumMemberName("error")]
+    Error,
+
+    /// <summary>Critical conditions that require immediate attention.</summary>
+    [JsonStringEnumMemberName("critical")]
+    Critical,
+
+    /// <summary>Action must be taken immediately to address the condition.</summary>
+    [JsonStringEnumMemberName("alert")]
+    Alert,
+
+    /// <summary>System is unusable and requires immediate attention.</summary>
+    [JsonStringEnumMemberName("emergency")]
+    Emergency
+}