How to use the @bentley/imodeljs-frontend.IModelApp.tools function in @bentley/imodeljs-frontend

this._measureNamespace!.readFinished.then(() => {
      // restart the tool.
      console.log("MeasurePoints onExecute called, args", args);
      IModelApp.tools.run("Measure.Points");
    })
      .catch((err) => { console.log(err); });

public static executeCommand = () => {
    // first load the plugin
    IModelApp.tools.run("Plugin", ["MeasurePoints.js"]);
  }

public static async initialize(): Promise {
    if (undefined === this.namespace) {     // only need to do this once
      this.namespace = IModelApp.i18n.registerNamespace("MarkupTools");
      IModelApp.tools.register(SelectTool, this.namespace);
      IModelApp.tools.registerModule(redlineTool, this.namespace);
      IModelApp.tools.registerModule(textTool, this.namespace);
    }
    return this.namespace.readFinished; // so caller can make sure localized messages are ready.
  }

private _processInputValue(inputValue: string): boolean {
    let currentKeyin = "";
    let foundTool: typeof Tool | undefined;

    if (this.state.currentToolId && this.state.currentToolId.length > 0) {
      foundTool = IModelApp.tools.find(this.state.currentToolId);
      // istanbul ignore else
      if (foundTool)
        currentKeyin = foundTool.keyin;
    }

    // istanbul ignore next
    if (inputValue !== currentKeyin) {
      const inputValueLower = inputValue.trim().toLowerCase();
      foundTool = IModelApp.tools.getToolList()
        .find((tool: typeof Tool) => tool.keyin.toLowerCase() === inputValueLower || tool.englishKeyin.toLowerCase() === inputValueLower);

      if (!foundTool) {
        this._outputMessage(UiFramework.translate("keyinbrowser.couldNotFindTool"));
        return false;
      } else {
        const currentToolId = foundTool.toolId;
        // istanbul ignore else
        if (this._isMounted)
          this.setState({ currentToolId });
      }
    }

    return true;
  }

private _execute = () => {
    if (this.props.execute) {
      this.props.execute();
    } else {
      const thisTool: typeof Tool | undefined = IModelApp.tools.find(this.props.toolId);
      // istanbul ignore else
      if (thisTool)
        (new thisTool()).run();
    }
  }

      handler: () => { IModelApp.tools.run(this._toolName, ViewClipDecorationProvider.create()); setFocusToHome(); },
      parent: div,

      click: () => IModelApp.tools.run("SVTSelect"),
      tooltip: "Element selection",

        click: () => IModelApp.tools.run("View.Standard", IModelApp.viewManager.selectedView, i),
      }));

      handler: () => IModelApp.tools.run("ViewClip.Clear", ViewClipDecorationProvider.create()),
      parent: div,

const handleClear = () => {
    IModelApp.tools.run(ViewClipClearTool.toolId, ViewClipDecorationProvider.create());
    setPopupOpen(false);
  };