Spidermon's core functionality provides some useful features that allow you to build your monitors on top of it. The library depends on six, jsonschema and python-slugify.
If you want to set up any notifications, additional monitoring dependencies will help with that.
If you want to use schematics validation, you probably want validation.
So the recommended way to install the library is by adding both:
pip install "spidermon[monitoring,validation]"