Build, buy or both?

Every company we talk to already pays for some AI. A writing assistant here, a meeting summariser there, a chatbot on the website. The question is rarely whether to use AI. It is which work deserves more than a subscription.

The honest answer is that most of it doesn’t. And the part that does usually needs both: things you buy and things you build.

When buying is enough

An off-the-shelf tool is the right choice when three things are true.

The work is generic. Summarising a meeting, rewriting an email, translating a document, drafting a first version of a job ad. Every company does it roughly the same way, so a product built for everyone fits you well.

It needs no live data. The input is whatever the person pastes in, and the output goes back to that person. Nothing has to be read from your ERP or written into your CRM.

Nobody owns an outcome. It makes individuals faster, but no team has signed up to move a number with it. If it gets worse next month, someone switches tools and nothing breaks.

For this kind of work, building your own is a waste of money. Buy the tool, set some sensible rules on what data goes into it, and move on.

When a process deserves its own agent

The picture changes when the work runs through your systems and your rules. A process deserves its own agent when:

1. It lives in your systems. The agent has to read the order, the ticket history, the supplier file or the price list, and write back to them.
2. There is a number. First response time, hours spent on admin, stock left unsold. A team owns it and wants it to move.
3. Some decisions need a person. Refunds, promises, anything that cannot be undone. Those need approval rules that match how your company works, not how a vendor imagined companies work.
4. It is specific to you. Your policies, your exceptions, your tone, the thing only Maria knows. A generic tool does not know any of it and you cannot teach it properly.

No product sold to everyone can do all four for you. It doesn’t know your systems, it can’t own your number, and its rules are someone else’s.

The both pattern

In practice, the answer for most serious processes is both.

You buy the commodity. The language models themselves, from the big model providers. Hosting, email delivery, search, the plumbing. Nobody should build their own model to answer supplier emails.

You build what is yours. The agents, the approval rules and the shared memory. That is where your process, your policies and your judgement live, and it is the part that makes the difference between a demo and a system you can rely on.

This split also protects you. Models improve and prices change every few months. When the agents, rules and memory are yours, swapping the model underneath is an engineering task, not a migration. The marketplace system we built uses models from several providers at once, each chosen for the job, and the system does not depend on any single one.

Buy the model. Build the part that knows your business.

Who owns what

Whatever you build, ask who owns it at the end. In our projects the answer is simple. The agents run in your environment and the memory is in your systems. You own the code, the prompts and the data, so you can run them without us.

That matters more than it seems. A process that runs on an agent you do not own is a process someone else can reprice, change or switch off.

A quick test

If every answer is no, buy it. If two or more are yes, the process probably deserves its own agent, built on bought models, with rules and memory that belong to you.