Open · Adversarial · via MCP

Irrational

A field guide to the mistakes your mind makes, and an engine that refracts your decision into the biases bending it.

↓ audit a decision below, free, in your own AI


The engine

Audit a decision you're facing.

Irrational writes the adversarial prompt; your own AI runs it. We have no model of our own, and nothing you type is stored.

  1. 1 Describe your decision
  2. 2 Copy the prompt (or open it in your AI)
  3. 3 Paste into your AI to get the audit
Open the prompt in:

We run no model; nothing you type is stored.

…or watch it work on a pre-built scenario

The call

Don't greenlight the big-bang rewrite. Carve off the worst module first (strangler-fig), behind the current interface, with a hard 3-month checkpoint.

confidence ~25% · top bias: sunk cost
The audit

This is a System 1 call wearing a suit, fluent, certain, and missing every number that matters. Watch what is actually steering it.

Sunk cost, the “two months on a POC” are gone either way, but they are doing most of the talking. You are reasoning from what you have spent, not from what the next month returns.
Planning fallacy, “about six months” is a best-case, single-point guess with no reference class, and the POC tested the fun 20%, not the six years of edge-cases that are the other 80%.
Survivorship, “Stripe and others did it and won” quotes the visible survivors and steps over the graveyard of rewrites that quietly overran or were abandoned.
WYSIATI, “the old thing is beyond saving” is a confident verdict built on what is annoying today, it ignores the undocumented business logic the old system silently encodes.
Outside view. Big-bang rewrites of mature, in-production systems routinely run 2–3× the estimate, and a sobering share never fully replace the original. Against that base rate, “six months” is the floor, not the plan, anchor your timeline on your team’s own estimate-vs-actual history instead.
Premortem. Picture it a year out, failed: hidden rules surfaced mid-migration, you ended up running both systems at once, velocity dropped instead of rising, “six months” became eighteen, and leadership pulled the plug half-done, leaving two unfinished systems.
Sit with this
  • If you'd never built the POC, would a full rewrite still be the obvious move today?
  • What's your team's real estimate-vs-actual ratio on big projects, and why are you the exception this time?
  • What logic lives only in the old code that nobody fully understands, and what happens to it on cutover day?
  • Could an incremental strangler-fig capture ~80% of the velocity gain at ~20% of the risk?
The recalibration

Not “never rewrite.” The version that survives scrutiny: an incremental strangler-fig: carve off the worst module first, behind the existing interface, with a hard 3-month checkpoint and a timeline built from your own track record. Treat the POC as a learning artifact, not a down payment.

original full rewrite ~25% · incremental path at recoverable risk: moderate–high

Verdict-first, every bias tied to the words you wrote. Browse all 22 biases →

Why not just ask your AI?

Because your AI is trained to agree, to help you execute the framing you walked in with. Irrational assumes you're biased, refuses to validate, and argues the other side, and every bias it names is cited to its primary source, not improvised.