I just learned that the Document Foundation develops The ODF Toolkit. This includes an ODF Validator tool. The name of this tool is "odfvalidator", which is nearly identical to OPF's "odf-validator". Since both are tools for validating ODF documents, this could be a major source of future confusion/misunderstandings.
From what I can see TDF's "odfvalidator" already existed a few years when development of the OPF tool started. This makes me wonder if it would be wise to rename it to something else? Since the software is still in alpha stage, doing so would be relatively painless since it is not widely know/used yet.
Also, I think it would be useful if the readme/documentation explained how the OPF validator differs from the TDF one.