Command-line tools are externally authored scripts that can be run from the Analyst's Notebook Connector for Esri toolbox. They allow integration of tasks such as importing chart items with geospatial data, or opening specific files or applications.
The command-line tools are configured in the following file:
<Installation Directory>\Foundation Module\Modules\i2.Mapping.Esri.CommandlineModule.dll.config
This file contains an example tool that can be used as the basis for your own configuration.
For more information about command-line tools, see the relevant Microsoft™ documentation.