Start with the workflow, then choose the tool
Buy an existing AI product when it can do the job within your quality, access, integration, and ownership requirements. Build when a material gap remains and closing it is worth the cost of operating a custom system.
There’s a third option: use what you already own differently. A process change or better configuration may remove the constraint without a new platform. Include that option in the comparison.
The goal is a working capability that changes the business result. Neither a license nor a custom application guarantees it.
Write requirements from real work
Choose a representative set of tasks. Include the difficult cases, exceptions, and failed attempts that your team handles today. Describe a good result in terms the people doing the work can judge.
For a document workflow, “can summarize documents” is too broad. The useful questions concern which documents, whose permissions, which sources must support the answer, what review happens next, and what an unacceptable error looks like.
Separate requirements you must meet from features that would be convenient. Then ask a vendor to demonstrate the actual work, using information you’re permitted to share. Use the same acceptance criteria for a proposed custom build.
Compare the full operating model
| Question | Existing product | Custom build |
|---|---|---|
| Does it fit? | Test the core workflow and its exceptions. | Define the scope and acceptance tests. |
| Who can access the data? | Check the product’s configuration and contract. | Design and verify the access model. |
| How does it connect? | Validate the integrations you need. | Budget for integration and ongoing changes. |
| Who runs it? | Name an internal owner and support path. | Name an owner, support path, and maintenance budget. |
| What happens if you leave? | Check export and transition options. | Specify code, documentation, and handover. |
Security depends on the implementation and operating controls. “Custom,” “cloud,” and “on-premise” are descriptions of an approach, not proof that a system meets your requirements.
Count more than the first invoice
Compare the costs over a period that matches the decision. Include licenses or infrastructure, integration, training, support, maintenance, evaluation, and staff time spent correcting or checking the output.
Don’t count the same gain twice. Time saved is not automatically cash saved. Revenue potential is not realized revenue. An eliminated contract is a different result from a team completing more work.
Our private equity case makes the distinction concrete: the system surfaced a deal the firm later closed. Deal value is the right label for that headline; it isn’t software-generated profit.
Make the next decision small enough to test
Run a bounded evaluation before making a broad commitment. Give the existing tool, process change, and proposed build the same job to do. Decide in advance what good output, acceptable effort, and successful handover look like.
If no option meets the criteria, inspect the criteria and the workflow. A missing definition, unreliable source data, or an unclear owner can make every tool look bad.
That happened in a biotech product launch: conflicting expert labels and an unresolved definition sat underneath the model problem. Clarifying the target was part of making the product work.
The right answer can be “buy,” “build,” or “change the process first.” What matters is that the evidence supports it.
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