public sealed class AnnotationProperties 

// Creates a new annotation template for the specified annotation layer.
await QueuedTask.Run(() =>
  {
    Inspector insp = null;
    // get the anno feature class
    var fc = annotationLayer.GetFeatureClass() as ArcGIS.Core.Data.Mapping.AnnotationFeatureClass;

    // get the feature class CIM definition which contains the labels, symbols
    var cimDefinition = fc.GetDefinition() as ArcGIS.Core.Data.Mapping.AnnotationFeatureClassDefinition;
    var labels = cimDefinition.GetLabelClassCollection();
    var symbols = cimDefinition.GetSymbolCollection();

    // make sure there are labels, symbols
    if (labels.Count == 0 || symbols.Count == 0)
      return;

    // find the label class required
    //   typically you would use a subtype name or some other characteristic
    // in this case lets just use the first one

    var label = labels[0];

    // each label has a textSymbol
    // the symbolName *should* be the symbolID to be used
    var symbolName = label.TextSymbol.SymbolName;
    int symbolID = -1;
    if (!int.TryParse(symbolName, out symbolID))
    {
      // int.TryParse fails - attempt to find the symbolName in the symbol collection
      foreach (var symbol in symbols)
      {
        if (symbol.Name == symbolName)
        {
          symbolID = symbol.ID;
          break;
        }
      }
    }
    // no symbol?
    if (symbolID == -1)
      return;

    // load the schema
    insp = new Inspector();
    insp.LoadSchema(annotationLayer);

    // ok to assign these fields using the inspector[fieldName] methodology
    //   these fields are guaranteed to exist in the annotation schema
    insp["AnnotationClassID"] = label.ID;
    insp["SymbolID"] = symbolID;

    // set up some additional annotation properties
    AnnotationProperties annoProperties = insp.GetAnnotationProperties();
    annoProperties.FontSize = 36;
    annoProperties.TextString = "My Annotation feature";
    annoProperties.VerticalAlignment = VerticalAlignment.Top;
    annoProperties.HorizontalAlignment = HorizontalAlignment.Justify;

    insp.SetAnnotationProperties(annoProperties);

    var tags = new[] { "Annotation", "tag1", "tag2" };

    // use daml-id rather than guid
    string defaultTool = "esri_editing_SketchStraightAnnoTool";

    // tool filter is the tools to filter OUT
    var toolFilter = new[] { "esri_editing_SketchCurvedAnnoTool" };

    // create a new template 
    var newTemplate = annotationLayer.CreateTemplate("new annotation template", "description", insp, defaultTool, tags, toolFilter);
  });

//In your config.daml...set the categoryRefID
//<tool id="..." categoryRefID="esri_editing_construction_annotation" caption="Create Anno" ...>

//Sketch type Point or Line or BezierLine in the constructor...
public class ProSnippetAnnotationConstructionTool : MapTool
{
  public ProSnippetAnnotationConstructionTool()
  {
    IsSketchTool = true;
    UseSnapping = true;
    SketchType = SketchGeometryType.Point;
  }

  /// <summary>
  /// Handles the completion of a sketch operation and creates an annotation feature based on the provided geometry.
  /// </summary>
  protected async override Task<bool> OnSketchCompleteAsync(Geometry geometry)
  {
    if (CurrentTemplate == null || geometry == null)
      return false;
    // Create an edit operation
    var createOperation = new EditOperation
    {
      Name = string.Format("Create {0}", CurrentTemplate.Layer.Name),
      SelectNewFeatures = true
    };
    var insp = CurrentTemplate.Inspector;
    var result = await QueuedTask.Run(() =>
    {
      // get the annotation properties class
      AnnotationProperties annoProperties = insp.GetAnnotationProperties();
      // set custom annotation properties
      annoProperties.TextString = "my custom text";
      annoProperties.Color = ColorFactory.Instance.RedRGB;
      annoProperties.FontSize = 24;
      annoProperties.FontName = "Arial";
      annoProperties.HorizontalAlignment = HorizontalAlignment.Right;
      annoProperties.Shape = geometry;
      // assign annotation properties back to the inspector
      insp.SetAnnotationProperties(annoProperties);
      // Queue feature creation
      createOperation.Create(CurrentTemplate.Layer, insp);
      if (!createOperation.IsEmpty)
      {
        // Execute the operation
        return createOperation.Execute(); //Execute and ExecuteAsync will return true if the operation was successful and false if not
      }
      else
        return false;
    });
    return result;
  }
}