Two investments, two clocks
Harness
Infrastructure
What it does
Sets the AI up to do one job well
Lets that work run safely across the business
Time to build
Weeks, improving fast
Months to years, compounding
When it is weak
Confident answers nobody checks
Pilots that never reach production
Who owns it
The business team and its AI builders
Technology, data and risk leaders
Models are converging, so the advantage moves to the two layers you own. They run on different clocks. A harness can be built and improved in weeks, one use case at a time. Infrastructure takes years and compounds: every clean dataset and connected system makes the next use case cheaper. The practical path is to start the harness on data you already trust, and build the infrastructure in the order your use cases need it.
Everyone can hire the same genius. The advantage is in how you set them up, and the company they walk into.
What to do next
- 1
Start with one job.
Pick a valuable, well-bounded use case and build its harness: instructions, context, tools, memory and checks.
- 2
Fix data in use-case order.
Clean and connect the records that first use case needs. Each one makes the next use case cheaper.
- 3
Measure the system.
Keep a fixed set of test questions and re-run them after every change to the model, the harness or the data.
Questions leaders ask
What is an AI harness?
Everything around a model that sets it up to do a specific job: its instructions, the context it is given, the tools it can use, its memory, and the checks on its work.
Is a better model enough?
Rarely on its own. A 2026 study found the same model’s score varied by almost ten percentage points depending on the harness alone, more than switching between leading models.
What makes data AI-ready?
Data that is accurate, current, connected across systems and governed, so the AI can find the right information and is allowed to use it. Gartner advises aligning data work to specific AI use cases.
The harness results come from software tasks, where the evidence is strongest today.
Sources
- LangChain (February 2026). Improving Deep Agents with harness engineering. Terminal-Bench 2.0.
- Zhang et al. (2026). Stop Comparing LLM Agents Without Disclosing the Harness. arXiv preprint.
- Gartner (February 2025). Lack of AI-Ready Data Puts AI Projects at Risk.
- Informatica (2025). CDO Insights 2025. 600 data leaders.
- Drexel LeBow and Precisely (2026). Data Integrity and AI Readiness. 505 data leaders.