Setting a tool content root path can help you keep your tools consistent with standards if the project or the standards drawings are moved during the project lifecycle.
When tools on the project tool palettes point to the tool content root path specified in the project settings, the content root path is created as a variable (%AECPROJECT_DIR%) in the XML definition of the tool. When the tool content root path in the project settings is changed, the path of the tools is changed accordingly.
For example, if all project tools point to content stored under <Project Root Folder>\Standards\Content\Content 1\, you can move the content to <Project Root Folder>\Standards\Content\Content 2\, adjust the tool content root path in the project setup accordingly, and all tools will now point correctly to <Project Root Folder>\Standards\Content\Content 2.
Another use case for changing the tool content root path would be if a user wants to work offline, and for that purpose creates an e-transmit package of the project and its tool content files. When the e-transmit package is unpacked on the local computer, the path to the content files will have changes. If it was P:\ <Project Root Folder>\Standards\Content\Content, it could now be C:\ <Project Root Folder>\Standards\Content\Content. If the tool content root path is redirected to the user’s C drive, and all content will remain valid.
Later, when the drawings the user modified offline are copied back to the main project on the P server, the content root path will automatically change back to P:\ <Project Root Folder>\Standards\Content\Content, as this is the path in the main APJ file.