How to use Codex to its full potential.

2026 Day 170. #TechDays.

Recently I have been using Codex more often than ever. It has immensely changed the development process for me. Often I find myself with a lot of free time to explore other ideas while Codex. These have led to interesting experimentations and findings.

Getting the most out of Codex requires better prompting.

For large writes or rewrite, it’s better to generate a good structured prompt.

Gather your technical requirements and start writing as if you are describing the details to your junior. Be as descriptive as possible in terms of design and technical details, leave as little space for ambiguity as possible.

Once you are done, give it to ChatGPT and ask it to translate into a technical requirement using markdown for Codex. It is going to give you the document that you should review before passing it along to Codex.

Before you forward the instructions to Codex, make sure you have some boilerplate code set up — npx create-react-app or something similar to make sure that Codex does not waste time and tokens on things that are minimal effort.

This should give Codex enough context and strict instructions to give you something close enough if not exactly what you want.

Once you have perfected your prompt, you might want to fine tune Codex with a skills.md or an agents.md file.

These can be project specific or general ones. Thsee provide greater context about your development style, formatting, libraries you like to prefer (GSAP over Motion.dev) and so on.

They can also contain ever clearer instructions regarding how API calls need to be made, the headers, request type, and sample response. This helps remove ambiguity by providing the exact definitions that the agent needs to implement in your project.

Many libraries that I have been working with (PayloadCMS) have included the skills.md files within their project which helps the agent get access to the entire documentation in a more accessible format at the same level as the project. This is not a single file but multiple files arranged in various folders to provide detailed documentation without having the agent read the entire thing multiple times.

Think of Codex as someone who will be support you no matter what.

This can be rather counter-intuitive when you are trying to get things done. Like a senior who does not stop you from committing to production without testing, Codex will implement what you ask of it without hesitation. The idea might be great in your head, but when you look at the real situations you might find that it seems to be problematic.

A recent example comes to mind. I learned about Shopify Headless and wanted to create a template with it so I could use it all the time. I looked at the costs and found that headless costs the same as Shopify but using Headless meant you had way more freedom on the front-end.

So I headed to build a template for it. Only when I started the execution did I realise that Shopify Headless is the backend, will not let you edit your website visually, if I was building this for non-technical users, this was kind of important. So I thought of adding Payload for the visual editing bit.

Then it hit me. Shopify Headless costs the same as Shopify. I would additionally have to pay for Next.js app hosting + Payload database hosting for the exact same functionality just with a more customisable front-end?

The stupidity of my decision was apparent only too late. I had gotten a little carried away with the excitement of a new tech. Replacing Shopify with Medusa.js might an interesting prospect as this would do away with the cost of the headless and the cost Shopify takes for every sale.

Always take a step back, learn more before committing yourself to a project or you will be wasting your usage. Codex, for the most part, will not stop you, so you must be able to think more than in the moment.

Codex is a great tool for aiding your development. My main task with Codex is adding metadata, trying out different written content, or vibe-coding the boring sections.

It is definitely a great tool and you can use it to make fun projects. You will learn very little about what you are building and thus it might not be as useful. There are many more people with an idea that are executing them with Codex and launching it out there.

If you are looking to make money off of these projects then tread carefully. Codex can one-shot many things, and if your project was built with a single prompt, someone else can duplicate it with one too and open source it. If the tool was useful, the community will embrace the open source version.

Whatever you build cannot be the entire product unless you plan on making enterprise level software. Be smarter than this. Use Codex to fix issues and try to review as much as possible. Fix Codex’s problems to find where it does not shine and always needs you.

See you tomorrow.