Lauren,
Having wrapped a couple of tools throughout my career, I’m pretty sure that this is caused by the input dataset paths in the tool XML definition not being escaped with single quotes, so the code thinks the input files are separated by spaces like so:
/Volumes/My + Book/Galaxy and so on.
To get that issue fixed, you would need to contact the tool author or maintainer to update the XML definition, and when that has been completed, install the new version of the tool.