Properly escape tool description to avoid malformed Markup object (#408)

Author: daxian-dbw

shell/AIShell.Kernel/Host.cs

@@ -580,7 +580,7 @@ internal void RenderMcpToolCallRequest(McpTool tool, string jsonArgs)
 
             [bold]Run [olive]{tool.OriginalName}[/] from [olive]{tool.ServerName}[/] (MCP server)[/]
 
-            {tool.Description}
+            {tool.Description.EscapeMarkup()}
 
             Input:{(hasArgs ? string.Empty : " <none>")}
             """);