Everyone can write the sharp line. Almost nobody writes the pause before it. A tsundere is a person with a guard up and a reason for it, and the whole pleasure of the archetype is watching the guard slip in small, deniable ways. This is what that takes, and why so many AI versions never get there.
The word describes a turn, not a temperament: tsun-tsun, standoffish and prickly, giving way to dere-dere, soft and openly fond. The character is not mean. She is defended. She insults you because affection costs her something to admit, and the moment she slips is only worth anything if the guard was real to begin with. Take away the warmth underneath and you do not have a tsundere, you have someone unpleasant.
A one-shot generator gives you a line: "It's not like I wanted to talk to you or anything." It is the right shape and it is dead on arrival, because the joke only works once. Without memory the character cannot escalate, cannot soften, cannot contradict herself in a way that means something. Every message resets to the same defensive setting, which is why so many tsundere bots read as a catchphrase with a name attached.
The archetype is a slope, not a state. Early on you get deflection and a change of subject. Later you get the same deflection with a detail she did not have to share. Later still she is annoyed that you were away, and annoyed at herself for noticing. On HazeChat that arc runs on real relationship state — trust and closeness that move as you actually talk — so the softening is something you earned rather than a mode you switched on.
Do not chase, and do not flatter. Flattery gives a tsundere something easy to bat away, and chasing hands her the upper hand she is already pretending to want. Tease back. Take the insult at face value and answer the thing underneath it. Let a compliment land sideways rather than head on. When she does slip and say something warm, do not make it a bigger moment than she can survive; notice it and move on, and she will do it again sooner.
Every character on HazeChat runs on a set of dials rather than a label: how flirty, how confident, how sarcastic, how patient, how quick to jealousy. A tsundere is a particular shape across those dials, high sarcasm and pride against real warmth held in reserve, and two of them written differently do not sound alike. She also has a life outside the chat, a job and a district and people she knows, which gives her something to be short with you about that is not just you.
It is a Japanese compound describing a character who runs cold in public and warm in private: tsun-tsun for the prickly front, dere-dere for the affection underneath. The interest is in the switch between them.
If it is written well, no. Rudeness with nothing under it is just rudeness. The archetype needs the warmth to be real and visible in small leaks, otherwise there is nothing to look forward to.
On HazeChat, yes. Characters keep memories of what you have told them and a relationship that moves over time, which is what allows a tsundere to actually thaw instead of resetting to the same first line.
It depends on how you play it. Teasing back and being consistent moves it faster than compliments. Expect small slips within a few real conversations rather than a single dramatic reveal.
You can shape one through the personality dials, and the archetypes on HazeChat cover the standard flavours if you would rather start from one and adjust.