In this article
Before you start
This page sits inside the interview process overview, which shows how rounds fit together.
Why interviewers ask this
A company that lets you use AI tools can no longer judge you by typing speed or recall of algorithms, so it judges decisions instead. Sierra, an AI company, says it removed its coding and algorithms interviews and replaced them with an AI-native onsite. In its account the old format mostly measured mechanics, and the new one makes it easier to gauge agency and judgement.
A weak answer to "how does this round work?" describes a coding test: you get a spec and submit code. A strong answer describes the phases and says what each one shows. A Staff-level answer also names the trade-off the company accepts. Open-ended tasks are harder to standardize, so Sierra writes criteria that do not depend on what the candidate builds and runs interviews in pairs to improve calibration.
AI-engineering take-homes from first principles
- AI-engineering take-home
- An AI-engineering take-home is a work-sample task in which a candidate builds a small product on top of AI models, or with AI coding tools, mostly alone, and is judged on the build and on how well they explain the choices behind it.
- Scoping
- Scoping is the act of deciding which parts of a task to build, cut or leave rough inside a fixed time limit, so that what you hand in works from start to finish and you can say why the rest was left out.
- Review
- Review is the closing phase of the round in which you demo what you built and answer questions about its design and about how you used AI, so the interviewer sees your reasoning as well as your result.
In plain words
Think of a design studio that hands you a small commission and a day. They do not expect a finished building. They watch which rooms you draw first, what you drop when time runs short, and how you explain the plans. The analogy breaks in one place: here the studio also lets you bring power tools and then asks how you used them.
In one precise sentence, the round has you plan a product, build it with tools you choose inside a fixed window, and defend it in a demo. Sierra's Build phase is an onsite session, not a take-home. Candidates report that other companies run similar tasks as take-homes you do alone.
Step 1: Plan: scope the product
Plan defines a product to build: in Sierra's format it is a working session in which the candidate and the interviewer agree what product to build. A take-home has no live session, so you do this step yourself, in writing, before you touch code.
Input: an open prompt or a short brief. Output: a short scope note that says what you will build, what you will cut and why. Sierra frames judgement as how you scope what to build within the time constraints, so a good note spends the time on what is unique and leaves out generic screens such as sign-in. You now have a plan the next step can follow.
Step 2: Build: use the tools you choose
The Build phase runs two hours with the AI tools and frameworks of the candidate's choice. In Sierra's format the interviewer steps out, and the candidate has complete freedom to pivot or adjust scope along the way.
Input: your scope note. Output: something that runs and that you can show. The window varies by company. Candidates report longer solo builds of several hours, sometimes with a recorded walkthrough, so read the stated limit. Agency, as Sierra frames it, is whether you pivot when you get stuck. You now have a working path to demonstrate.
Step 3: Review: the demo and the question about AI use
The Review phase is a demo plus a discussion of how you used AI. In Sierra's words the interviewers "also dig into how they used AI along the way."
Input: what you built. Output: a clear account of it. Expect questions that go past the demo to your design reasoning, such as the data model and how the design would extend, and to what production would need; this list is advice, not a published one. The follow-up to prepare is therefore "how did you use AI?" A strong answer says where the tool drafted code, where you rewrote or rejected its output, and how you checked that the result worked. You now know all three phases and what each one shows.
Step-by-step description
- Define a product to build.
- Build with tools you choose.
- Demo, then explain your AI use.
- Plan defines a product to build.
- The Build phase runs two hours with the AI tools and frameworks of your choice.
- Review is a demo plus a discussion of how you used AI.
What do you hand in, and what happens after you submit?
Sierra's format is one published example of the plan, build and review pattern, not the definition of a take-home. As general advice rather than a sourced fact, a take-home has you receive a brief and a time cap, then hand in a repository, a README with run instructions, a note on what you scoped out and why, a note on how you used AI, and sometimes a recorded walkthrough. A debrief or review call may follow, where you explain the design and your AI use.
Formats candidates report
These shapes come from candidate reports and are not verified here: a longer solo build of several hours, sometimes with a recorded walkthrough; a short capped build where heavy AI use is encouraged; an AI-allowed timed exercise on an assessment platform graded on design, testing and optimization; and an assessment that scores how you interact with the AI tool. Check how yours will be graded before you start.
How to split the time in a build window
A build window needs a written time plan, because the demo is a phase of its own. An illustrative split of a 120-minute window gives 18 minutes to scope, 78 minutes to build and 24 minutes to demo prep.1 Building takes the largest share of the window, and demo prep still gets its own block.
For a purely illustrative 300-minute window, the same shares give 45, 195 and 60 minutes.1 The shares are an example, not a company rule. If the window includes a recorded walkthrough, move a few minutes from build to demo prep, because you must plan and record the explanation as well as run the product. Adjust the shares to the stated time cap and to what the brief asks you to hand in.
| Phase | Share | Minutes (illustrative) |
|---|---|---|
| Scope | 15% | 18 |
| Build | 65% | 78 |
| Demo prep | 20% | 24 |
Text description of the diagram
- An illustrative split of a 120-minute window gives 18 minutes to scope, 78 minutes to build and 24 minutes to demo prep.
- Building takes the largest share of the window, and demo prep still gets its own block.
Knowing it is half the job. Saying it is the other half.
Interview Clozo is an AI interview copilot for real interview rounds: it hears the question and puts a strong answer on your screen, and you say it in your own words. See the features or how it works.
Start Free Trial →The Staff-level answer
How would you approach an AI-engineering take-home?
I treat it as three phases: plan, build, review. First I spend a few minutes writing the scope: what I will build, what I will cut, and why. Then I build with whatever AI tools are allowed, and if I get stuck I change the plan instead of pushing on. I leave time to demo a working path, and I can say where the AI drafted code, where I rewrote it and how I checked it. The trade-off is depth against finish: I would rather ship a smaller thing that runs and explain what I cut than a half-built larger one.
What makes it Staff-level is the trade-off at the end and the habit of accounting for AI use, which shows judgement and not only output.
The rubric
This rubric is advice built from Sierra's stated focus on agency and judgement plus general interview practice, not a company scoring sheet.
| Dimension | Weak answer | Strong answer | Staff answer |
|---|---|---|---|
| Scoping | Tries to build everything in the brief. | Cuts scope and says what was cut. | Cuts boilerplate, keeps the unique part, and justifies it by the time limit. |
| Agency | Keeps pushing the same approach when stuck. | Changes approach when blocked. | Names the point where it pivoted and what the pivot saved. |
| Review | Shows a demo with no design reasoning. | Explains the data model and abstractions. | Also says how the design would extend and what breaks first. |
| Use of AI | Cannot say where AI helped. | Says what the tool drafted and what was rewritten. | Also describes how output was checked and when the tool was wrong. |
| Path to production | Stops at "it runs on my machine". | Lists what is missing for production. | Ranks the gaps by risk and says which to fix first. |
Three variants of this question
Is an AI-engineering take-home done alone or live?
It depends on the format. Sierra's build is an onsite session where the interviewer steps out for two hours, while other companies run similar tasks as take-homes you do on your own, as candidates report. Read the instructions for where and how long.
What are they actually scoring?
Sierra names agency (pivoting when stuck) and judgement (scoping within the time limit), and it asks how you used AI. A strong answer shows these and clear design reasoning, not only working code.
What if I get stuck halfway through?
Change the approach or the scope instead of freezing. Sierra frames pivoting when stuck as agency, and says candidates have complete freedom to pivot or adjust scope.
Common mistakes
- "I'll build everything in the brief." (wrong) Sierra frames judgement as how you scope within the time constraints, so an overstuffed plan shows weak scoping. (right) "I cut X and Y to finish the part that is unique, and here is why."
- "I won't mention how I used AI in the demo." (wrong) Interviewers ask about it. (right) "The tool drafted this part, I rewrote that part, and I checked it by running these cases."
- "Every company allows AI, so I'll use it everywhere." (wrong) Candidate reports differ by company, so one company's rule says nothing about another's. (right) "I read the instructions first and follow them."
- "I'll build until the clock runs out." (wrong) You then demo cold. (right) "I reserve a block of the window to prepare a working demo and my explanation."
- "I'll spend the first hour on sign-in and settings screens." (wrong) That is rarely the core idea. (right) "I stub it or skip it when allowed and spend the time on the core idea."
Follow-up questions
How long does an AI-engineering take-home take?
Sierra's build phase is two hours. Candidates report windows that range from short capped builds to longer solo projects, so always read the stated limit. The AI-assisted coding interview page covers how a shorter, live version is graded.
Do all companies allow AI in a take-home?
Not in the same way everywhere. Sierra lets candidates choose their own tools and then asks how they used them. Candidates report other variants: a short capped build where heavy AI use is encouraged, an assessment-platform exercise with a built-in AI tool, and an assessment that scores how you interact with AI tools. Read the instructions and follow them exactly.
How do multi-agent and context-engineering take-homes differ?
A multi-agent task asks you to coordinate several model-driven workers, and a context-engineering task asks you to decide what information goes into the model's context. Both still follow the plan, build and review pattern; see multi-agent and context-engineering take-homes.
Which take-home should I prepare for first?
Prepare for the one in your process. The agent take-home, the retrieval-augmented generation take-home and the machine-coding take-home each apply this pattern. The forward deployed and applied AI engineer rounds page covers a neighbouring role.
- An AI-engineering take-home is an open-ended build judged on scoping, pivots, review and how you explain your AI use.
- Sierra's version has three phases: Plan, a two-hour Build with tools of your choice, and a Review.
- Scope to the time limit; Sierra says building onsite produces higher signal than the old format.
- Reserve a block of the window for the demo, and read each company's AI policy.
Sources
- The AI-native interview — Sierra (Iyengar, Asemanfar, Wang), 22 Apr 2026
- Attribution 4.0 International (CC BY 4.0) deed — Creative Commons, 25 Nov 2013
