Button ToolTip

this.addButton(new ImageButton(xPos, yPos, xSize, Ysize, xPosInResourse, xPosInResourse, SizeofResourse, ResourseLocation, e -> {
			Mod.PACKET_HANDLER.sendToServer(new ModGui.ButtonPressedMessage(0, x, y, z));
			ModGui.handleButtonAction(entity, 0, x, y, z);
			//You can create usual button in MCreator GUI builder and edit, excluding the handlers part
		})
		{public void renderToolTip(MatrixStack ms, int mouseX, int mouseY){
			ModGuiWindow.this.renderTooltip(ms, "Your text", mouseX, mouseY);
			//You also can use constant variable for xPos and yPos of ToolTip
			}
		}
);

This code for 1.16.5
You also can find good tutorial here - https://mcreator.net/forum/83507/added-image-buttons-guis