Use the extensive debug messages to troubleshoot in case of unexpected problems. These debugging messages are useful because an API would be difficult to debug otherwise. User can turn on debug messages with a certain profile option. These messages can be written to a log file as well.
The TCA API is an integrated set of code designed in a highly modular fashion, resulting in codes that are easy to understand, maintain and extend.
The modular approach defaults and validates users who enter information; default information not provided by the user and calls the appropriate entity handler to perform the business related tasks.