public static IReadOnlyList<KeyValuePair<string,string>> MakeEnvironmentArray( 
   object workspace,
   object packageWorkspace,
   object scratchFolder,
   object scratchGDB,
   object scratchWorkspace,
   object outputCoordinateSystem,
   object geographicTransformations,
   object extent,
   Nullable<int> retryOnFailures,
   object parallelProcessingFactor,
   Nullable<int> recycleProcessingWorkers,
   object cellAlignment,
   object cellSize,
   object cellSizeProjectionMethod,
   object mask,
   object snapRaster,
   object configKeyword,
   Nullable<int> autoCommit,
   Nullable<bool> maintainAttachments,
   Nullable<bool> maintainSpatialIndex,
   Nullable<bool> preserveGlobalIds,
   Nullable<bool> transferGDBAttributeProperties,
   Nullable<bool> qualifiedFieldNames,
   Nullable<bool> transferDomains,
   object XYDomain,
   object XYResolution,
   object XYTolerance,
   object MDomain,
   object outputMFlag,
   Nullable<double> MTolerance,
   Nullable<double> MResolution,
   object ZDomain,
   Nullable<double> outputZValue,
   object outputZFlag,
   object ZResolution,
   object ZTolerance,
   object randomGenerator,
   object cartographicCoordinateSystem,
   Nullable<double> referenceScale,
   object cartographicPartitions,
   Nullable<int> annotationTextStringFieldLength,
   object pyramid,
   object rasterStatistics,
   object compression,
   object tileSize,
   object resamplingMethod,
   object nodata,
   Nullable<bool> terrainMemoryUsage,
   object tinSaveVersion,
   object coincidentPoints,
   object S100FeatureCatalogueFile,
   object processorType,
   Nullable<int> gpuId,
   string processingServer,
   string processingServerUser,
   object processingServerPassword,
   Nullable<bool> matchMultidimensionalVariable,
   Nullable<bool> unionDimension,
   object baDataSource,
   object baNetworkSource,
   Nullable<bool> baUseDetailedAggregation,
   Nullable<bool> maintainCurveSegments,
   Nullable<bool> overwriteoutput
)

{
  var parameters = Geoprocessing.MakeValueArray(@"C:\data\data.gdb\HighwaysUTM11", @"C:\data\data.gdb\Highways_extent");
  var ext = Geoprocessing.MakeEnvironmentArray(extent: "460532 3773964 525111 3827494");
  var result = Geoprocessing.ExecuteToolAsync("management.CopyFeatures", parameters, ext);

  // use the result as needed
}

{
  var environments = Geoprocessing.MakeEnvironmentArray(overwriteoutput: true);

  string toolName = "Snap_edit";  // or use edit.Snap

  // Snap tool takes multiple inputs each of which has
  // Three (3) parts: a feature class or layer, a string value and a distance
  // Each part is separated by a semicolon - you can get example of sytax from the tool documentation page
  var snapEnv = @"'C:/SnapProject/fgdb.gdb/line_1' END '2 Meters';'C:/SnapProject/fgdb.gdb/points_1' VERTEX '1 Meters';'C:/SnapProject/fgdb.gdb/otherline_1' END '20 Meters'";

  var infc = @"C:/SnapProject/fgdb.gdb/poly_1";

  var snapParams = Geoprocessing.MakeValueArray(infc, snapEnv);

  GPExecuteToolFlags tokens = GPExecuteToolFlags.RefreshProjectItems | GPExecuteToolFlags.GPThread | GPExecuteToolFlags.AddToHistory;

  IGPResult snapResult = Geoprocessing.ExecuteToolAsync(toolName, snapParams, environments, null, null, tokens).Result;

  // use the result as needed
}

{
  string tool2 = "analysis.Buffer";
  List<MapPoint> list =
  [
    MapPointBuilderEx.CreateMapPoint(1.0, 1.0),
    MapPointBuilderEx.CreateMapPoint(1.0, 2.0),
    MapPointBuilderEx.CreateMapPoint(2.0, 2.0),
    MapPointBuilderEx.CreateMapPoint(2.0, 1.0),
  ];

  Multipoint multiPoint = MultipointBuilderEx.CreateMultipoint(list);
  var spatial_ref = SpatialReferenceBuilder.CreateSpatialReference(3857);

  // Note: Needs QueuedTask to run
  var args3 = Geoprocessing.MakeValueArray(multiPoint, "memory\\Buffers", "800 meters");

  var env1 = Geoprocessing.MakeEnvironmentArray(outputCoordinateSystem: spatial_ref);
  var messages = new List<string>(); // list to collect all output messages
  var cts = new CancellationTokenSource();
  Geoprocessing.ExecuteToolAsync(tool2, args3, env1, cts.Token);
}

{
  string openProjectPath = @"D\DATA\IGPHistoryItemTestProject\IGPHistoryItemTestProject.aprx";
  Project.OpenAsync(openProjectPath);
  MapProjectItem mapProjItem = Project.Current.GetItems<MapProjectItem>().FirstOrDefault(item => item.Name.Equals("Map", StringComparison.CurrentCultureIgnoreCase));

  // Note: Needs QueuedTask to run
  var map = mapProjItem.GetMap();
  var ftrLayer = map.Layers[0] as FeatureLayer;
  string tool1 = "management.GetCount";
  var args1 = Geoprocessing.MakeValueArray(ftrLayer);
  var env = Geoprocessing.MakeEnvironmentArray(overwriteoutput: true);
  GPExecuteToolFlags executeFlags = GPExecuteToolFlags.AddToHistory;
  var t = Geoprocessing.ExecuteToolAsync(tool1, args1, env, null, null, executeFlags);

  IEnumerable<IGPHistoryItem> hisItems = Project.Current.GetProjectItemContainer(Geoprocessing.HistoryContainerKey) as IEnumerable<IGPHistoryItem>;

  string hitemID = "";
  string hitemToolPath = "";
  IGPResult hitemGPResult = null;
  DateTime hitemTimeStamp;

  foreach (var hitem in hisItems)
  {
    // common IGPHistoryItem and Item properties
    hitemID = (hitem as Item).ID;
    hitemToolPath = hitem.ToolPath;
    hitemGPResult = hitem.GPResult;
    hitemTimeStamp = hitem.TimeStamp;

    // use the properties as needed
  }
}