How do I make a custom tooltip with Plotly express?

Question

I am trying to make custom text appear when I hover over the points in the scatter chart. This is my code to generate the chart.

import plotly.io as pio

#data
fig = dict({
    "data": [{"type": "scatter3d",
              "x": [4.5, 2, 3, 18.8],
              "y": [1, 3, 2, 23],
              "z": [1, 4, 3, 2]}],


    "layout": {"title": {"text": "A map of Human Space"}}
     
})


#Generate graph
pio.show(fig)