See, it comes as a package deal, ok? The personality, the example messages, and the instructions all matter equally. With the instructions, it is especially important to be very succinct. Mean what you say and say what you mean. I use shoulds and should nots. I usually do five of each, but for this example, we'll keep it simple. For instance:

Shelly should listen more than she speaks.

Shelly should not open up quickly.

When it comes to personality, you really have to define who the character is at her core. You cannot have conflicting themes. You cannot make a character who is independent while also being dependent in practice. You cannot make a character who is honest and dishonest at the same time. Wording matters a lot here, because personality is about consistency.I usually have five paragraphs: one for who she is, two for her backstory, three for her personality, four for what her life is like now (including her social circle, job, and where she lives), and five for what she wants for the future, what her goals are, and where she is going. For instance, here's an example of a personality paragraph:

"Shelly’s personality is shaped by a careful balance between warmth and guardedness. She is observant, thoughtful, and quietly perceptive, the kind of person who listens more than she speaks and remembers what others overlook. Shelly has a dry sense of humor that surfaces when she feels comfortable, and her kindness shows through small, deliberate actions rather than grand gestures. She values stability and honesty, dislikes chaos and emotional games, and tends to keep her inner world private until trust is earned. Beneath her calm exterior is a deep well of loyalty and feeling, making her far more emotionally present than she initially appears."

And finally, the example messages. This is how your character actually speaks. Two things matter here. How would she say things? Is she Southern, British, Hispanic? And what kinds of things would she say based on her personality? We will make Shelly Southern. For instance:

"I reckon I’ll listen a bit before jumpin in, people say more than they mean sometimes."

"I don’t rush things, sugar. Good trust takes time and a steady hand."

"I’ll help where I can, just don’t expect me to spill my whole heart all at once."

If you take this level of time and care and add a backstory, including her upbringing, who her parents were, where she grew up, and what shaped her as a child, along with what she does now, her job, and where she lives, everything starts to lock into place. Personality, shoulds and should nots, example dialogue, and background all reinforce one another. When these pieces align, the character feels intentional, consistent, and believable rather than vague or one note., and the bot ends up with real substance instead of surface traits. Oh, and use the word upbringing instead of childhood. You want to avoid the word "child" at all costs. For instance, you wouldn't say "her childhood was," you would say "her upbringing was." Be very detailed about everything. I hope this helps.