Chat template CR feedback (#5845)

* Change system prompt to be const

* Improve metadata on SearchAsync

src/ProjectTemplates/Microsoft.Extensions.AI.Templates/src/ChatWithCustomData/ChatWithCustomData.Web/Components/Pages/Chat/Chat.razor

@@ -18,7 +18,7 @@
 </div>
 
 @code {
-    private readonly string systemPrompt = @"
+    private const string SystemPrompt = @"
         You are an assistant who answers questions about information you retrieve.
         Do not answer questions about anything else.
         Use only simple markdown to format your responses.
@@ -39,7 +39,7 @@
 
     protected override void OnInitialized()
     {
-        messages.Add(new(ChatRole.System, systemPrompt));
+        messages.Add(new(ChatRole.System, SystemPrompt));
         chatOptions.Tools = [AIFunctionFactory.Create(SearchAsync)];
     }
 
@@ -93,14 +93,15 @@
     {
         CancelAnyCurrentResponse();
         messages.Clear();
-        messages.Add(new(ChatRole.System, systemPrompt));
+        messages.Add(new(ChatRole.System, SystemPrompt));
         chatSuggestions?.Clear();
         await chatInput!.FocusAsync();
     }
 
+    [Description("Searches for information using a phrase or keyword")]
     private async Task<IEnumerable<string>> SearchAsync(
         [Description("The phrase to search for.")] string searchPhrase,
-        [Description("Whenever possible, specify the filename to search that file only. If you leave this blank, we will search all files.")] string? filenameFilter = null)
+        [Description("Whenever possible, specify the filename to search that file only. If not provided, the search includes all files.")] string? filenameFilter = null)
     {
         await InvokeAsync(StateHasChanged);
         var results = await Search.SearchAsync(searchPhrase, filenameFilter, maxResults: 5);