Why make one model debate itself?

Forcing both sides surfaces the strongest counterarguments to your position instead of letting the model agree with you. It is a cheap, fast way to stress-test a plan, a thesis, or a design decision before you commit.

What is the rebuttal rule for?

Without it, each side just restates its opening. The rebuttal rule requires every turn after the first to directly engage the opponent's last point, which produces a real exchange rather than two parallel monologues.

Should I ask for a verdict?

A neutral closing verdict is useful when you want a recommendation, but it can flatten nuance. If you mainly want to see the arguments, turn the verdict off and judge for yourself.

Can the personas be experts or roles?

Yes. Naming concrete roles — "a security engineer" vs "a product manager", or "the optimist" vs "the skeptic" — gives each side a consistent lens and makes the debate sharper than generic Pro and Con.

Debate Prompt Builder

Debate prompt builder

The fastest way to find the holes in an idea is to argue against it as hard as you argue for it. An LLM will happily do both — if you set the structure up right. Left to its own devices it drifts into agreement or produces two disconnected lists. This builder writes a prompt that assigns two named personas, fixes the number of rounds, sets an argument style, and enforces rebuttals so you get a genuine back-and-forth you can learn from.

How it works

You give the tool a proposition, two persona names, a round count, and an argument style. It generates a prompt instructing the model to open with each persona’s strongest case, then alternate for the chosen number of rounds. The rebuttal rule requires every turn after the opening to engage the opponent’s previous point directly, which is what turns parallel monologues into a real exchange. Optionally it asks for a neutral verdict that weighs both sides at the end. Distinct personas keep each voice consistent so the two positions stay clearly separated.

Tips and example

Name real roles, not Pro and Con. “A privacy advocate” vs “a growth lead” produces far more concrete arguments than generic for-and-against labels.
Use the steelman style for decisions. When you are about to commit to something, ask each side to present the strongest version of its case so you are not knocking down strawmen.
Three rounds is usually enough. The first round states positions, the second produces the real clash, and the third resolves loose ends. More rounds tend to repeat.
Skip the verdict to stay in control. If you want to judge for yourself, turn the verdict off and read the exchange as raw material for your own decision.