Tri-Inspector/Editor.Samples/Styling/Styling_PropertyTooltipSample.cs

using System;
using TriInspector;
using UnityEngine;

public class Styling_PropertyTooltipSample : ScriptableObject
{
    [PropertyTooltip("This is tooltip")]
    public Rect rect;

    [PropertyTooltip("$" + nameof(DynamicTooltip))]
    public Vector3 vec;

    public string DynamicTooltip => DateTime.Now.ToShortTimeString();
}