Argument overrideSuggestionsT(IStringTooltip... suggestions);
Argument overrideSuggestionsT(Collection<IStringTooltip> suggestions);
Argument overrideSuggestionsT(Function<CommandSender, IStringTooltip[]> suggestions);
Argument overrideSuggestionsT(BiFunction<CommandSender, Object[], IStringTooltip[]> suggestions);

StringTooltip none(String suggestion);
StringTooltip of(String suggestion, String tooltip);

Example - An emotes command with string suggestion tooltips

Say we want to create a simple command to provide ingame emotes between players. For example, if you did /emote wave Bob, you'll "wave" to the player Bob. For this example, we'll use the following command syntax:

/emote <emote> <target>

First, we'll declare our arguments. Here, we'll use the overrideSuggestionsT method, along with the StringTooltip.of(String, String) method to create emote suggestions and include suitable descriptions:

List<Argument> arguments = new ArrayList<>();
arguments.add(new StringArgument("emote")
	.overrideSuggestionsT( 
        StringTooltip.of("wave", "Waves at a player"),
        StringTooltip.of("hug", "Gives a player a hug"),
        StringTooltip.of("glare", "Gives a player the death glare")
	)
);
arguments.add(new PlayerArgument("target"));

Finally, we declare our command as normal:

new CommandAPICommand("emote")
	.withArguments(arguments)
	.executesPlayer((player, args) -> {
		String emote = (String) args[0];
		Player target = (Player) args[1];
		
		switch(emote) {
		case "wave":
			target.sendMessage(player.getName() + " waves at you!");
			break;
		case "hug":
			target.sendMessage(player.getName() + " hugs you!");
			break;
		case "glare":
			target.sendMessage(player.getName() + " gives you the death glare...");
			break;
		}
	})
	.register();

public interface IStringTooltip {
	public String getSuggestion();
	public String getTooltip();
}

Example - Using IStringTooltip for custom items

Let's say we've created a simple plugin which has custom items. For a custom item, we'll have a super simple class CustomItem that sets its name, lore and attached itemstack:

public class CustomItem implements IStringTooltip {

	private ItemStack itemstack;
	private String name;
	
	public CustomItem(ItemStack itemstack, String name, String lore) {
		ItemMeta meta = itemstack.getItemMeta();
		meta.setDisplayName(name);
		meta.setLore(Arrays.asList(lore));
		itemstack.setItemMeta(meta);
		this.itemstack = itemstack;
		this.name = name;
	}
	
	public String getName() {
		return this.name;
	}
	
	public ItemStack getItem() {
		return this.itemstack;
	}
	
	@Override
	public String getSuggestion() {
		return this.itemstack.getItemMeta().getDisplayName();
	}

	@Override
	public String getTooltip() {
		return this.itemstack.getItemMeta().getLore().get(0);
	}
	
}

Let's also say that our plugin has registered lots of CustomItems and has this stored in a CustomItem[] in our plugin. We could then use this as our input for suggestions:

CustomItem[] customItems = new CustomItem[] {
	new CustomItem(new ItemStack(Material.DIAMOND_SWORD), "God sword", "A sword from the heavens"),
	new CustomItem(new ItemStack(Material.PUMPKIN_PIE), "Sweet pie", "Just like grandma used to make")
};  //
	
new CommandAPICommand("giveitem")
	.withArguments(new StringArgument("item").overrideSuggestionsT(customItems)) // We use customItems[] as the input for our suggestions with tooltips
	.executesPlayer((player, args) -> {
		String itemName = (String) args[0];
		
		//Give them the item
		for(CustomItem item : customItems) {
			if(item.getName().equals(itemName)) {
				player.getInventory().addItem(item.getItem());
			}
		}
	})
	.register();

Argument safeOverrideSuggestionsT(Tooltip<S>... suggestions);
Argument safeOverrideSuggestionsT(Collection<Tooltip<S>> suggestions);
Argument safeOverrideSuggestionsT(Function<CommandSender, Tooltip<S>[]> suggestions);
Argument safeOverrideSuggestionsT(BiFunction<CommandSender, Object[], Tooltip<S>[]> suggestions);

Tooltip<S> none(S object);
Tooltip<S> of(S object, String tooltip);
Tooltip<S>[] arrayOf(Tooltip<S>... tooltips);

Example - Teleportation command with suggestion descriptions

Say we wanted to create a custom teleport command which suggestions a few key locations. In this example, we'll use the following command syntax:

/warp <location>

First, we'll declare our arguments. Here, we use a LocationArgument and use the safeOverrideSuggestionsT method, with a parameter for the command sender, so we can get information about the world. We populate the suggestions with tooltips using Tooltip.of(Location, String) and collate them together with Tooltip.arrayOf(Tooltip<Location>...):

List<Argument> arguments = new ArrayList<>();
arguments.add(new LocationArgument("location")
    .safeOverrideSuggestionsT((sender) -> {
        return Tooltip.arrayOf(
            Tooltip.of(((Player) sender).getWorld().getSpawnLocation(), "World spawn"),
            Tooltip.of(((Player) sender).getBedSpawnLocation(), "Your bed"),
            Tooltip.of(((Player) sender).getTargetBlockExact(256).getLocation(), "Target block")
        );
    }));

In the arguments declaration, we've casted the command sender to a player. To ensure that the command sender is definitely a player, we'll use the executesPlayer command execution method in our command declaration:

new CommandAPICommand("warp")
	.withArguments(arguments)
	.executesPlayer((player, args) -> {
	    player.teleport((Location) args[0]);
	})
	.register();