I Gave Two AI Models Six Words and Got a Guitar Fretboard. Then Things Got Honest.

Some prompts reveal more of AI’s limitations than its strengths. This was one of them.

I typed six words. The AI built something impressive and got almost everything wrong. Here is what that means for how we evaluate AI output.

I typed six words into a duel on VibeCode Arena.

“Design a guitar with all the key notes represented on strings.”

That was it. No extra context. No design specs. No colour palette. No instructions about interactivity or layout or what clicking a note should do.

Just six words. And then I watched two AI models interpret them completely on their own.

What came back genuinely surprised me.

What actually happened

Both models built something called an Interactive Guitar Fretboard.

All twelve notes laid out across the top. C, C#, D, D#, E, F, F#, G, G#, A, A#, B. Six strings running horizontally. Click a note and green highlights appear showing its positions across the fretboard.

Not what I expected from six words.

But here is where I have to be honest, because this is the part that actually makes it an interesting challenge.

When I clicked A# the interaction worked. A# lit up in multiple positions across all six strings, which is correct — it does appear at different frets on every string in standard tuning. The concept is right and the underlying logic is mostly there.

But a guitarist looking at this would immediately spot what is missing.

No fret numbers. You can see a green dot on a string but you have no idea if that is fret 1 or fret 11. For a tool that is supposed to show you where notes live on the neck, that is a significant gap. A guitarist needs to know “A# is at fret 6 on the low E string” — not just see a highlight floating somewhere on a line.

No sound whatsoever. You click a note and it highlights visually but you hear nothing. For a guitar tool that is a pretty fundamental gap — half the point of learning the fretboard is training your ear alongside your eye. Right now it is a purely visual reference with no audio feedback at all.

No fret markers either. Real guitars have dot markers at frets 3, 5, 7, 9, and 12. Visual landmarks that help you orient yourself on the neck. Without them the fretboard is harder to read than it needs to be.

The neck also looks slightly short. Standard guitars run to at least 12 frets. A few of the higher positions on certain strings might be getting cut off entirely.

So the AI got the concept right. The interaction works. But the output has four clear problems that make it not quite ready for real use.

No sound whatsoever. You click a note and it highlights visually but you hear nothing. For a guitar tool that is a fundamental missing piece — the whole point of learning the fretboard is training your ear and your eye at the same time. Right now it is a silent visual map.

The note positions are not accurate. This is the most important one. When you click a note the highlighted positions across the strings do not always match where that note actually sits in standard tuning. For something that is supposed to teach you the fretboard, getting the positions wrong is a pretty serious problem.

No fret numbers. You can see a green dot on a string but you have no idea if that is fret 1 or fret 11. A guitarist needs to know “A# is at fret 6 on the low E string” — not just see a highlight floating somewhere on a line.

No fret markers. Real guitars have dot markers at frets 3, 5, 7, 9, and 12. Visual landmarks that help you orient yourself on the neck. Without them, the fretboard is harder to read than it needs to be.

The neck also looks slightly short. Standard guitars run to at least 12 frets. A few of the higher positions on certain strings might be getting cut off entirely.

Concept right. Execution incomplete. That is exactly what makes it the right kind of open challenge.

Why is this prompt specifically interesting

A guitar fretboard is one of those things that sounds simple until you actually think about what it requires.

You need to understand music theory enough to place notes correctly. You need to think about visual hierarchy — what is a string, what is a fret, what is a note position. You need to handle interactivity in a way that feels intuitive. You need the whole thing to fit in a browser window without feeling cramped.

Six words produced something that handles all of that.

That is not nothing. That is actually impressive. And it opens up a lot of questions about what a better version of this could look like with more iteration, more perspective, more people bringing different ideas to the same starting point.

Which is exactly why I made it a challenge.

The challenge is live and the fretboard is yours to improve

I have opened this up on VibeCode Arena. Anyone can jump in, take the base fretboard output, direct AI to improve it, and submit their version.

Think about what this could become with the right iteration:

Sound — click a note and actually hear it play. The fretboard goes from visual to musical instantly.

Chord diagrams — select a chord and see all the finger positions light up simultaneously.

Scale highlighter — toggle a scale and watch the relevant notes across all strings illuminate.

Dark mode — because every developer tool looks better in dark mode. This is not negotiable.

Visual redesign — make it look like an actual guitar instead of a grid. Wood grain, tuning pegs, the whole thing.

Practice mode — the fretboard calls out a note and you have to find it. Simple quiz mechanic but immediately turns it into a learning tool.

Any one of these takes the base output from functional to genuinely impressive. And you do not need to implement it yourself — you direct AI to do it and the platform scores what comes back.

Build the version I could not build alone.

Join the challenge here: https://vibecodearena.ai/share/afc85b04-2031-4b33-8a70-caf14197ac6d

What the duel format taught me about this specific prompt

I have been using AI tools for a while now. I have a set of models I default to, a way of prompting I have settled into, a rough mental model of what each tool handles well.

The blind duel broke all of that in a single session again.

Codestral-2508 handled the music theory layout with real precision. The note positions were accurate. The string spacing felt right. I would not have reached for Codestral for something like this without the blind format forcing me to evaluate it on merit.

That is the pattern I keep finding on VibeCode Arena. My default models are not always the right models. My habits are not always serving me. The blind vote is a fast, low-stakes way to find out where your assumptions are wrong.

One duel per day on a prompt you actually care about is probably one of the highest-value things you can do for your AI judgment right now.

Come make the fretboard better

The challenge is open. The base output is solid. The ceiling is high.

Whether you add sound, redesign the visuals, build a practice mode, or do something I have not thought of — I want to see what you make.

Challenge link: https://vibecodearena.ai/share/afc85b04-2031-4b33-8a70-caf14197ac6d

Six words got us here. Imagine what the right iteration gets us to.

I Gave Two AI Models Six Words and Got a Guitar Fretboard. Then Things Got Honest. was originally published in Coinmonks on Medium, where people are continuing the conversation by highlighting and responding to this story.