Update src/ModelContextProtocol.Core/Client/McpClient.Methods.cs

Co-authored-by: Stephen Toub <stoub@microsoft.com>

Author: mikekistler

src/ModelContextProtocol.Core/Client/McpClient.Methods.cs

@@ -107,9 +107,6 @@ public async ValueTask<IList<McpClientTool>> ListToolsAsync(
         RequestOptions? options = null,
         CancellationToken cancellationToken = default)
     {
-        var serializerOptions = options?.JsonSerializerOptions ?? McpJsonUtilities.DefaultOptions;
-        serializerOptions.MakeReadOnly();
-
         List<McpClientTool>? tools = null;
         string? cursor = null;
         do