Rethinking What a ChatGPT & MCP App Is

Building ChatGPT & MCP Apps requires a different mental model than building traditional web apps. The instinct is to bring an entire product into the chat interface, but that usually misses the point. A better question is: how can this app improve the chat experience itself?

Chat is already excellent at generating text. Where it struggles is with things humans process visually. Lists, structure, comparison, spatial context. Many real workflows are visual, yet the interface often collapses everything into a wall of words.

The Problem with Color Palettes in Chat

A small example makes this obvious. When I ask ChatGPT to generate a color palette for a website, I usually get a list of hex codes. The information is technically correct, but not very usable. To evaluate the palette, I end up copying each hex code into Google or a color picker just to see what it looks like.

A Simple App That Fixes the Experience

To fix this, I built a very small Color Palette app. It does one thing: take the hex codes that ChatGPT already generated and render them visually. Large color blocks, with the hex value and color name underneath.

Nothing about the intelligence changed. It's the same output, just presented in a way that's immediately useful. This is where ChatGPT & MCP Apps really shine.

Building the App with a Single Prompt

What surprised me most was how little effort it took. I used Fractal and created the app with a single prompt. Here is the exact prompt I used:

Create a palette generator app using the below spec:

The app is called when the user asks chatGPT to generate a color palette, or generate a [number of colors]-color palette

ChatGPT will create the color palette and pass the hex and color names to the app's input

The app uses the hex to generate a beautiful UI of the color palette, clearly show the colors, with the hex and name underneath

Breaking Down the Anatomy of the Prompt

You can think of this prompt as having four distinct parts.

1. A General Description of What You Want to Build

This is where you name the app and state its purpose.

In this case: "Create a palette generator app."

This gives the system a clear mental model of what you're trying to build before any details are introduced.

2. When the App Should Be Called

This defines the trigger conditions.

Here, the app is invoked when the user asks ChatGPT to generate a color palette, including cases like "generate a 5-color palette". This step is important because it ties the app directly to a user intent in the conversation.

3. What Input the App Receives from ChatGPT

Next, you specify the data contract between ChatGPT and the app.

In this example, ChatGPT generates the palette itself and passes the hex codes and color names into the app's input. ChatGPT is the intelligence layer. The app doesn't need to reason about colors, it just consumes structured data.

4. What the App Does with That Input

Finally, you describe how the app should transform or use the input.

Here, the app renders a visual UI showing the colors, with the hex values and names underneath. No additional logic is required, it's purely a presentation layer.

This case is intentionally simple. The app displays exactly the information ChatGPT provides, just in a more usable format. Other apps can do much more, like calling an external API to take actions or transform data.

Iterating with a Second Shot

After using the app once, I realized I wanted one more small improvement. I added a button so I wouldn't have to type the same follow-up every time: "No I don't like this palette, give me another one".

That small change turned it into a two-shot app. From there, you can keep testing and adjusting it until it feels natural to use in the chat.

The Takeaway

The most effective ChatGPT & MCP Apps are not full products squeezed into chat. They are small, focused tools that remove friction at a specific moment in the conversation. When you design with that mindset, even a simple app can meaningfully upgrade the experience.

If you want to learn more about the ChatGPT & MCP Apps ecosystem and how to build apps, can watch the full YouTube playlist here: Watch the YouTube Playlist

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