In this article
Before you start
The behavioral interview questions guide covers the wider topic.
The phrase "ambiguous case interview engineer" has no official definition in engineering hiring. This page reads it as two situations that candidates meet: a behavioral prompt such as "tell me about a time you faced ambiguity," and a coding or system design task whose requirements are left vague on purpose. The page does not cover consulting-style business cases.
Why interviewers ask this
A vague prompt shows what you do before anyone hands you a complete plan. Northwestern University's career office describes the STAR approach as a strategy to structure your responses to behavioral interview questions. An ambiguity story applies that structure to unclear work.
Design and coding rounds carry the same signal. A coach quoted in a prep-company guide to Meta's software engineer interviews says: "There is an expectation that you will have a strong level of autonomy, ownership, and dealing with ambiguity." This is a report from a prep guide, not a statement from Meta's own hiring pages.
A weak answer waits for instructions or starts building without asking. A strong answer shows how you turned an unclear task into a clear next step, and what you changed afterwards.
Handling ambiguity from first principles
- Ambiguous prompt
- An ambiguous prompt is a question or task that leaves the goal, the constraints or the success measure unstated, so two reasonable people could start in different directions. In an interview it is either a behavioral prompt about a past unclear situation or a coding or design task with missing requirements.
- Two-way door
- A two-way door is a decision that can be reversed cheaply, so you can act, measure the result and walk back if it is wrong. An Amazon interviewer says most solutions are two-way doors. A one-way door is a decision that is hard or costly to undo and deserves more deliberation.
In plain words
Picture walking through fog with a map that has blank patches. You mark what you can see. You say which patches are blank. You take a short path you could walk back. Then you look again.
The analogy breaks in one place. In an interview a person is watching, and you can ask that person questions.
In one precise sentence: handling ambiguity means separating the known from the unknown, stating what you assume, and choosing a step whose cost of being wrong is small.
Step-by-step description
- Separate known from unknown.
- Choose a step you can undo.
- Use STAR order, your own actions.
- Action gets the most seconds.
- Separate what you know from what you do not know before you act.
- Choose a reversible step, a two-way door, and say why it can be undone.
- Tell the story in STAR order and describe what you personally did.
- Give Action the most seconds of a spoken answer.
Step 1: Separate what is known from what is unknown
Separate what you know from what you do not know before you act. For a behavioral story, this is the Situation: say what was clear, what was missing and who could fill the gap. For a vague coding or design prompt, it is the clarifying questions.
The Meta guide advises to start by clarifying the requirements, then state your assumptions and check that they are reasonable with the interviewer. The guide advises: "Since this can be impossible in around 45 minutes, it's important to scope out the problem first."
Amazon's Dive Deep principle names the same habit: leaders "stay connected to the details, audit frequently, and are skeptical when metrics and anecdote differ" (Amazon, 2020).
Here is an illustrative example for a technical prompt: "design a notification service." An engineer asks who sends to whom, what scale to expect, what latency target applies, whether a message may be lost or sent twice (the delivery semantics) and how success is measured. Then the engineer states one assumption aloud, for example "I will assume one kind of sender and moderate scale; tell me if that is wrong." The reversible first design choice is a queue between the senders and the delivery workers, because the queue can be resized or swapped later without changing what senders call.
Input: a vague prompt. Output: a short list of knowns, unknowns and one stated assumption. You now know what the next step has to resolve.
Step 2: Decide the next reversible step
Choose a reversible step, a two-way door, and say why it can be undone. Amazon's principles state that many decisions and actions are reversible and do not need extensive study. An Amazon interviewer adds: "Most solutions will be 'two-way doors,' which means they can be changed and aren't set in stone" (Amazon News, 2023).
The same interviewer says you can "dive so deep that you lose sight of the bigger picture" (Amazon News, 2023), so a good answer shows both digging and acting. Dig enough to be informed, then act in a way you can walk back. The Amazon Leadership Principles page covers the wider list.
For a one-way door, slow down and name who must agree before you commit.
Input: your unknowns and assumption. Output: one step, how it is undone, and what you will measure.
Step 3: Tell the story in STAR order with your own actions
Tell the story in STAR order and describe what you personally did. Amazon's interviewer says candidates "need to focus on the STAR method; Situation, Task, Action, Results," and should "focus on actions they personally took in the situation rather than their team" (Amazon News, 2023). She suggests adding an Improvement at the end, which makes STARI (STAR plus Improvement).
Map the steps onto the shape. The Situation is the gap. The Task is what you were responsible for. The Action is the clarifying, the assumption and the reversible step. The Result is what happened, plus what you would change.
Use "I" for your decisions and "we" only for the outcome the team shared. The teamwork STAR page shows the same split on a collaboration question.
Step 4: Budget the seconds of a spoken answer
Give Action the most seconds of a spoken answer. Northwestern suggests 15% for Situation, 10% for Task, 50% for Action and 25% for Result, and says Action "should always be the longest part of your response". The Massachusetts Institute of Technology (MIT) career office suggests 20%, 10%, 60% and 10%. The two differ, so treat either as guidance, not a rule.
Applied to an illustrative 90-second answer, the shares become seconds, and both splits give Action the most time: 45 seconds under Northwestern's and 54 under MIT's.1
| Part | Northwestern share | Northwestern seconds | MIT share | MIT seconds |
|---|---|---|---|---|
| Situation | 15% | 13.5 | 20% | 18 |
| Task | 10% | 9 | 10% | 9 |
| Action | 50% | 45 | 60% | 54 |
| Result | 25% | 22.5 | 10% | 9 |
Text description of the diagram
- Applied to an illustrative 90-second answer, the shares become seconds.
- Both splits give Action the most time, 45 seconds under Northwestern's and 54 under MIT's, in an illustrative 90-second answer.
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
Tell me about a time you faced ambiguity.
On a platform team I was asked to make the nightly export better, with no definition of better. I first split what I knew from what I did not: I knew it failed for large accounts, but not whether users wanted speed or correctness. I asked the two teams that used it, wrote down my assumption that correctness mattered most, and shared it for objections.
Then I chose a step I could undo, a feature-flagged retry for the failing accounts, instead of a rewrite, because switching the flag off restored the old behavior. I judged the retry by the failure rate for large accounts, and the failures stopped for those accounts within a week, and the pattern showed us what to fix next. Next time I would write the assumption down before the first meeting.
The story is illustrative; use a real one of your own. What makes it Staff-level: it names the unknowns, shares the assumption so others can correct it, picks a step with a stated undo, and ends with what you would change.
The rubric
This rubric describes what a strong answer shows; it is not how any company scores.
| Dimension | Weak answer | Strong answer | Staff answer |
|---|---|---|---|
| Structure | Rambles through events in time order | Follows STAR order with a clear gap | Opens with the gap, then the decision, then the result |
| Clarifying | Asks nothing, or waits for full requirements | Asks targeted questions and notes assumptions | Separates known from unknown and shares the assumption for correction |
| Decision | Freezes, or builds a large plan | Takes a sensible next step | Takes a reversible step and says how it is undone |
| Ownership | Says "we" throughout | Describes personal actions | Owns the call and credits others for inputs |
| Learning | Stops at the outcome | States the result | States the result and what changes next time |
Three variants of this question
Interviewers ask about ambiguity in three common phrasings, reported by candidates and not claimed for any company:
Describe a time you made a decision with incomplete information.
Use the same story shape, but stress Step 2: name what was missing, the assumption you made, and the reversible step that limited the cost of being wrong.
How do you deal with ambiguous situations and problems?
Answer with a method, then one short example: list known and unknown, state an assumption, take a small undoable step, and set a way to check it. A method sounds more credible than saying you love ambiguity.
How do you start when a coding or design prompt is vague?
Ask clarifying questions, state your assumptions aloud and check them, then scope the problem before you design, as the Meta guide advises. Keep the first design small enough to change.
Common mistakes
- "I waited until the requirements were complete." (wrong) Amazon's principles say many decisions are reversible and do not need extensive study. (right) "I took a small reversible step while the rest was still being decided."
- "I started building straight away." (wrong) A vague prompt is a request to clarify first. (right) "I asked what success looked like and stated my assumptions before I began."
- "We decided to ..." (wrong) The interviewer wants your personal actions. (right) "I proposed the step, and the team agreed."
- "I love ambiguity." (wrong) It claims a feeling and shows no method. (right) "I make it concrete: known, unknown, assumption, next step, check."
- A story that ends at the outcome. (wrong) It leaves out what you learned. (right) End with what you would change, the Improvement of STARI.
Follow-up questions
How long should a STAR answer about ambiguity be?
Keep it short; the 90-second length used above is illustrative, and the published splits give Action half to 60% of it.
What if the interviewer will not answer my clarifying questions?
State your assumptions aloud and ask whether they are reasonable, then continue. Asking what the interviewer would prefer is a good habit beyond this prompt; see questions to ask in an interview.
Is it a bad sign to ask a lot of clarifying questions?
It can be, if it delays any plan. Amazon's interviewer says diving too deep risks delaying your plan of action (Amazon News, 2023). Ask the few questions that change your design, then commit to a reversible step.
When should I not take the fast route?
When the decision is a one-way door: hard or costly to undo. There, deliberate longer, say who must agree and describe the check you ran before committing.
What if I have no story about ambiguity?
Use a smaller one: a task with an unclear goal, a vague bug report or a missing spec. The shape matters more than the scale. The common interview questions guide helps you pick other stories to prepare.
- Separate what you know from what you do not know before you act.
- Choose a reversible step and say why it can be undone.
- Use STAR order and describe your own actions, not the team's.
- Give Action the most time; the published splits differ, so treat them as guidance.
- End with what you would change next time.
Sources
- Amazon Leadership Principles (official document) — Amazon, 1 Oct 2020
- An Amazon interviewer dives deep into how she uses the Leadership Principles — Amazon News, 23 Aug 2023
- Behavioral Interviewing & The STAR Approach — Northwestern University Career Advancement, 26 Oct 2026
- Using the STAR method for your next behavioral interview — MIT Career Advising & Professional Development, 26 Oct 2026
- Meta Software Engineer Interview (questions, process, prep) — IGotAnOffer (secondary), 26 Oct 2026
