Why don't you write the default value in the description in the inputs options?

[minsoo-web]

Background

I didn't realize that the default value of the fetch-depth option is 1 until I looked in the README
Of course, user should read the documentation before using it, but if the default value was included in the description, I could have solved this problem with a tooltip that appears on hover.

Suggestion

Why not include a default value in the description?

fetch-depth:
    description: 'Number of commits to fetch. 0 indicates all history for all branches and tags. Default value is 1'
    default: 1

like this?