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The Library of Congress BagIt spec does not impose any restrictions or requirements for the contents of bag-info.txt files. Those requirements are instead implemented by institutions themselves. The UTL bag-info specification outlines which metadata fields are required for all bags submitted to tape. See the UTL bag-info specification page for a detailed explanation of each field.
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Bagger
Bagger is a Java-based GUI bagging tool that is useful for creating a single bag at a time. Download the ZIP file here and extract the files somewhere easy to access, such as C:\bagger. On Windows, run “bagger.bat” in the “bin” folder. On Unix, run the “bagger” file (no extension) in the same folder.
When bagger Bagger opens, click “Create New Bag”, select the “UTL” profile from the drop-down menu in the window that appears, and fill out each field marked with a red “R” (Required). Optionally fill out any fields not marked as required.
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The Java-based Bagger program has a built-in validation tool. To use it, click "Open Existing Bag" from the top menu, and select a bag in the window that appears. It may take some time for larger bags to open. Once the bag has been opened, click "Validate Bag" on the top menu to begin the process of validating the manifest files. Note that opening a bag allows you to edit the contents of its bag-info.txt file, so be careful not to make any changes!
You can also use the bag_validator Python script to validate a bag or set of bags. By default, the script will validate all bags in /dps/write_to_tape, but you can specify a specific bag to be validated with the -i option followed by a path to a bag, or a list of bags with the -f option followed by a path to a text file that lists the location of many bags. Adding the -r option will validate all bags in all subdirectories of a given folder.
Bags created with Bagger can be validated using bag_validator, and bags created with Python or other command-line BagIt tools can be validated using Bagger. Use whichever tool is most convenient for you.