ARCADIA does define a set of rules to follow, as below:
ARCADIA rule example:
Only “leaf” Functions (those that are not broken down) can have input/output Ports. If a function is broken down into sub-functions, there is the need of the assignment of Functional Exchanges to the sub-functions of the parent Function.
Many of the ARCADIA rules such as the one you mention are checked by the Validation Rules. Just select the whole model or a Perspective in the explorer, or any model element, right click -> Validate. You can find the list of validation rules in the Preferences menu.