Address PR feedback: improve DebuggerDisplay implementations

- Show MimeType and byte length instead of base64 data for binary content
- Use string literals in DebuggerDisplay attribute where possible
- Make ToolResultContentBlock display more dynamic (show result or error)
- Show actual text content in PromptMessage when available

Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Author: Copilot

src/ModelContextProtocol.Core/Protocol/BlobResourceContents.cs

@@ -35,9 +35,10 @@ private string DebuggerDisplay
     {
         get
         {
-            const int MaxLength = 80;
-            string blobPreview = Blob.Length <= MaxLength ? Blob : $"{Blob.Substring(0, MaxLength)}...";
-            return $"Uri = {Uri}, Blob = {blobPreview}";
+            // Decode base64 to get actual byte length
+            int byteLength = Blob.Length * 3 / 4;
+            string mimeInfo = MimeType is not null ? $", MimeType = {MimeType}" : "";
+            return $"Uri = {Uri}{mimeInfo}, Length = {byteLength} bytes";
         }
     }
 }

src/ModelContextProtocol.Core/Protocol/ContentBlock.cs

@@ -402,9 +402,9 @@ private string DebuggerDisplay
     {
         get
         {
-            const int MaxLength = 80;
-            string dataPreview = Data.Length <= MaxLength ? Data : $"{Data.Substring(0, MaxLength)}...";
-            return $"MimeType = {MimeType}, Data = {dataPreview}";
+            // Decode base64 to get actual byte length
+            int byteLength = Data.Length * 3 / 4;
+            return $"MimeType = {MimeType}, Length = {byteLength} bytes";
         }
     }
 }
@@ -436,9 +436,9 @@ private string DebuggerDisplay
     {
         get
         {
-            const int MaxLength = 80;
-            string dataPreview = Data.Length <= MaxLength ? Data : $"{Data.Substring(0, MaxLength)}...";
-            return $"MimeType = {MimeType}, Data = {dataPreview}";
+            // Decode base64 to get actual byte length
+            int byteLength = Data.Length * 3 / 4;
+            return $"MimeType = {MimeType}, Length = {byteLength} bytes";
         }
     }
 }
@@ -542,7 +542,7 @@ public sealed class ResourceLinkBlock : ContentBlock
 }
 
 /// <summary>Represents a request from the assistant to call a tool.</summary>
-[DebuggerDisplay("{DebuggerDisplay,nq}")]
+[DebuggerDisplay("Name = {Name}, Id = {Id}")]
 public sealed class ToolUseContentBlock : ContentBlock
 {
     /// <inheritdoc/>
@@ -568,9 +568,6 @@ public sealed class ToolUseContentBlock : ContentBlock
     /// </summary>
     [JsonPropertyName("input")]
     public required JsonElement Input { get; set; }
-
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    private string DebuggerDisplay => $"Name = {Name}, Id = {Id}";
 }
 
 /// <summary>Represents the result of a tool use, provided by the user back to the assistant.</summary>
@@ -621,5 +618,35 @@ public sealed class ToolResultContentBlock : ContentBlock
     public bool? IsError { get; set; }
 
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    private string DebuggerDisplay => $"ToolUseId = {ToolUseId}, ContentCount = {Content.Count}, IsError = {IsError ?? false}";
+    private string DebuggerDisplay
+    {
+        get
+        {
+            if (IsError == true)
+            {
+                return $"ToolUseId = {ToolUseId}, IsError = true";
+            }
+
+            // Try to show the result content
+            if (Content.Count == 1 && Content[0] is TextContentBlock textBlock)
+            {
+                return $"ToolUseId = {ToolUseId}, Result = \"{textBlock.Text}\"";
+            }
+
+            if (StructuredContent.HasValue)
+            {
+                try
+                {
+                    string json = StructuredContent.Value.GetRawText();
+                    return $"ToolUseId = {ToolUseId}, Result = {json}";
+                }
+                catch
+                {
+                    // Fall back to content count if GetRawText fails
+                }
+            }
+
+            return $"ToolUseId = {ToolUseId}, ContentCount = {Content.Count}";
+        }
+    }
 }

src/ModelContextProtocol.Core/Protocol/PromptMessage.cs

@@ -53,5 +53,17 @@ public sealed class PromptMessage
     public required Role Role { get; set; }
 
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    private string DebuggerDisplay => $"Role = {Role}, ContentType = {Content.Type}";
+    private string DebuggerDisplay
+    {
+        get
+        {
+            // Show actual text content if it's a TextContentBlock
+            if (Content is TextContentBlock textBlock)
+            {
+                return $"Role = {Role}, Text = \"{textBlock.Text}\"";
+            }
+
+            return $"Role = {Role}, ContentType = {Content.Type}";
+        }
+    }
 }

src/ModelContextProtocol.Core/Protocol/Resource.cs

@@ -12,7 +12,7 @@ namespace ModelContextProtocol.Protocol;
 /// <remarks>
 /// See the <see href="https://github.com/modelcontextprotocol/specification/blob/main/schema/">schema</see> for details.
 /// </remarks>
-[DebuggerDisplay("{DebuggerDisplay,nq}")]
+[DebuggerDisplay("Name = {Name}, Uri = {Uri}")]
 public sealed class Resource : IBaseMetadata
 {
     /// <inheritdoc />
@@ -107,7 +107,4 @@ public sealed class Resource : IBaseMetadata
     /// </summary>
     [JsonIgnore]
     public McpServerResource? McpServerResource { get; set; }
-
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    private string DebuggerDisplay => $"Name = {Name}, Uri = {Uri}";
 }

src/ModelContextProtocol.Core/Protocol/TextResourceContents.cs

@@ -20,7 +20,7 @@ namespace ModelContextProtocol.Protocol;
 /// See the <see href="https://github.com/modelcontextprotocol/specification/blob/main/schema/">schema</see> for more details.
 /// </para>
 /// </remarks>
-[DebuggerDisplay("{DebuggerDisplay,nq}")]
+[DebuggerDisplay("Uri = {Uri}, Text = \\\"{Text}\\\"")]
 public sealed class TextResourceContents : ResourceContents
 {
     /// <summary>
@@ -31,7 +31,4 @@ public sealed class TextResourceContents : ResourceContents
 
     /// <inheritdoc/>
     public override string ToString() => Text;
-
-    [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    private string DebuggerDisplay => $"Uri = {Uri}, Text = \"{Text}\"";
 }