TestComplete provides scripting access to the objects "ProjectSuite" and "Project", however this access is read only.
When developing test suites with one or more projects used as script libraries for tools used in actual test projects, you can add your tool scripts as existing items to the projects you want to use them in.
This approach has the downside that you have to merge name mapping files if name mapping is necessary for your tools, for example if you have a project of setup scripts run with different parameters for different tests before the actual tests are executed.
When encountering such necessities a read/write access to the objects "ProjectSuite" and "Project" plus some "Execute" method would be much more convenient and you would not have to clutter neither your suites' GUI by adding the same tool scripts time and again to different projects, nor your projects' name mapping by adding the same tool scripts' name mapping content.
This would provide the test developer with a scripting equivalent of projects' and project suites' test item tab, which he could change during runtime.