“That’s not Agile” is a phrase I’ve often observed, usually from people espousing specific methodologies. What they usually mean is that you’re no longer following a specific approach exactly as written. That may be a good thing…
Whatever Agile software development methodology you have adopted, if you want to claim you’re being (authentically) Agile, you should be honestly subscribing to the following principles. Ask yourself if your ways of working are:
Agile responds to change pragmatically. It tries to adapt rather than relying on prediction, acknowledging that some things may not (or cannot) be known in advance.
Agile aims to reduce uncertainty. It achieves this by taking small steps towards its overall goal rather than multi-phase delivery.
Agile uses evidence to make informed decisions. It changes based on what has been produced or discovered along the way.
Agile’s success is based on working together, with shared responsibility. Everyone needs to understand the goal and how to contribute as a team, to reach it successfully.
That’s it. Moreover, being Agile means that while you value those principles, it doesn’t mean you’re bound by them in all situations. You should respond to changing situations, different circumstances and constraints. That’s being agile (the adjective) and that’s being authentically Agile (the noun).