How long does it take to build an AI agent?
Four to ten weeks for an agent running on real traffic. The model is not what takes the time. Scoping one job precisely, finding a source of truth for every fact it will state, and deciding when it hands over to a person are what fill the calendar.
5 min read
Where the weeks go
Roughly, and overlapping in practice rather than running strictly in sequence:
- Week 1, scope. One job, named precisely. An agent that answers where-is-my-order and reschedules deliveries can be built and tested. One that helps customers cannot. This week also produces the list of actions the agent may take, which is the security boundary.
- Weeks 1 to 2, the data it will stand on. Where every fact it states comes from, and whether that source is current. This is where projects actually slow down: not because an integration is hard, but because the answer turns out to live in three places that disagree.
- Weeks 2 to 4, build and evaluate. The agent, its tools, and twenty real examples from your own inbox with the answer you would have wanted. That set is how you know whether a change made it better or merely different.
- Weeks 4 to 6, escalation and edges. What makes it stop and fetch a person, and what that person receives. Then the failure modes: confident wrong answers, people pushing at the guardrails, latency under real load.
- Weeks 6 to 10, live and watched. Running on real traffic with someone reading transcripts, because the first week of real users finds things no test set did.
What makes it ten rather than four
- Data spread across several systems that disagree, so what is true has to be decided before it can be answered.
- An action with real financial consequence, which means a person reviewing output before it goes out.
- A regulated or safety-relevant answer that has to be right every time rather than usually.
What makes it four: one job, one source of truth, and a wrong answer that costs an apology.
The estimate to distrust is the one given before anyone has asked where your data lives. That question is the schedule.
Related questions
- How long does it take to build an AI agent?
- Four to ten weeks for one running on real traffic. Four weeks when it does one job against a single source of truth and a wrong answer costs an apology. Ten when the data lives in several systems that disagree, or when a person has to approve output before it goes out.
- What takes the longest when building an AI agent?
- Establishing a source of truth for every fact the agent will state. Integration work is predictable; discovering that the answer lives in three systems that disagree is what moves a timeline, because someone has to decide which one is right before anything can be built on it.
- Can you build an AI agent in a week?
- You can build a demo in a week. A demo answers the questions you thought of. The remaining weeks go on the questions real customers ask, the facts the agent gets confidently wrong, and what happens when it has to hand over to a person.
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