Hello,
Thank you for reaching out regarding this question. There isn't a log that will show failed API attempts. You can see successful actions in the administrative log but it will not show you if you're missing inputs etc.
If you can share your script the community may be able to help you out here.
Thanks,
Zach Sylvester
System/Network Administrator
SmarterTools Inc.
(877) 357-6278
www.smartertools.com