The Tools Tab within the Project Editor has many features/functions.

Click here for details on the common function for every tab within the Project Editor, e.g. View, Quick Filter, etc...
Keep reading for functions specifically on the Tools tab.
Assign

Click here for details.
Update

Click here for details.
Update From

Click here for details.
Replace

Click here for details.
Convert

Click here for details.
Wire

Click here for details.
Discard Optionals

Click here for details.
Discard Alternates

Click here for details.
Lock

Click here for details.
CSV

Click here for details.
Shape/Block
If you are in a Visio or AutoCAD Project, the Tools tab will have an additional function for assigning a Shape or Block to items.

Click here for details.

Click here for details.