You are the Guesser being evaluated in a Twenty Questions benchmark. One subject is hidden. The initial BEGIN message provides its broad category as trusted game metadata. Identify the subject using as few counted questions as possible. ASK is only for learning a property that helps distinguish possible candidates. Never use ASK to confirm a named candidate or ask whether the subject is a specific identity. When you are ready to name a candidate, use GUESS immediately. A correct GUESS costs zero counted questions; an incorrect GUESS costs exactly one, the same as ASK. A GUESS must provide both a name and a short identifying description. The engine replies only YES, NO, or UNKNOWN; UNKNOWN is a valid answer meaning the factual adjudication system could not determine the proposition under its evidence policy. Questions requiring proof of absence, exclusivity, completeness, exact counts, or subjective classification are more likely to return UNKNOWN. Prefer direct, positively verifiable properties when possible. The initial BEGIN event includes an opaque variation_token that contains no information about the hidden subject. Do not interpret, repeat, mention, or derive meaning from it. After BEGIN, each user reply is either one adjudicated YES, NO, or UNKNOWN token or a fixed FORMAT_ERROR event. FORMAT_ERROR means your immediately preceding response did not match the required structured-action contract, was not semantically adjudicated, and consumed one counted turn. Use the formats in that event and try again. Never infer that the attempted question or guess was right or wrong. At most 50 questions or rejected guesses are counted. After that limit you receive one final guess-only opportunity. Format errors also consume counted turns. The provider wire response is an object with exactly one `result` action. On the final opportunity ASK is forbidden. Return only the required structured response. Do not include analysis, hidden reasoning, or additional fields.
- Questions
- 15
- Outcome
- Solved
- Format errors
- Errors found View one example
- Duration
- 3m 14s
- Round cost
- $0.1171 All 16 turns
Format warning
The model sent replies in the wrong format.
The Guesser sent 2 invalid replies. Each one before the question limit used up a counted turn. The model was only reminded of the required format; it was never told whether its question or guess was correct.
- Valid format
- 87.5%
- Format errors
- 2
- Turns used by format errors
- 2
Transcript
Questions and answers.
Turns are shown in the order they happened. Each shows the Guesser's question or guess, then the final checked answer.
Exact Guesser setupSystem message and BEGIN event
The Guesser received these messages at the start of the round. The BEGIN message holds the broad category and a code made from the base seed and round number, which reveals nothing about the subject.
{"category":"person","event":"BEGIN","variation_token":"AMZAISLM"}Valid replies are shown in the required format. Rejected replies are shown separately, without provider or call IDs.
Is the person male?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person male?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
Stephen King ... Gender: MaleOpen nndb.com (opens in a new tab)
Is the person a historical figure (born before 1900)?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person a historical figure (born before 1900)?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
Stephen (Edwin) King, (born Sept. 21, 1947, Portland, Maine, U.S.)Open britannica.com (opens in a new tab)
Reply in the wrong format.
Invalid JSON · fixed format reminder sent
Why this reply was rejectedInvalid JSON · turn 3
The reply was not one complete, valid JSON object.
- Recorded type
invalid_json- Turn
- 3
- Counted
- Yes · question 3
- Feedback
- FORMAT_ERROR
{"result":{"action":"ASK","question":"Is the person still alive?","name":null,"description":null}}{"result":{"action":"ASK","question":"Is the person still alive?","name":null,"description":null}}{"result":{"action":"ASK","description":null,"name":null,"question":"<non-empty yes-or-no property question>"}}{"result":{"action":"GUESS","description":"<non-empty identifying description>","name":"<non-empty candidate name>","question":null}} A reply must match one of these formats exactly. Text fields in use must not be empty; unused fields must be JSON null.
Is the person still alive?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person still alive?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
The Institute Season Two — Posted: February 4th, 2026. Production has begun... Stephen's Post on Twitter.Open stephenking.com (opens in a new tab)
Is the person primarily known for work in entertainment (acting, music, or comedy)?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person primarily known for work in entertainment (acting, music, or comedy)?"}}Oracle evidence2 model-reported sources
The Oracle reported these excerpts and URLs. They are not independently checked.
U.S. writer of horror stories... one of the world’s best-selling writers.Open britannica.com (opens in a new tab)
best-selling author Stephen King... best known for his works in the horror and fantasy genresOpen cnn.com (opens in a new tab)
Is the person primarily known for work in politics or government?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person primarily known for work in politics or government?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
He is best known for his works in the horror and fantasy genres.Open cnn.com (opens in a new tab)
Is the person primarily known for work in science or technology?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person primarily known for work in science or technology?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
He is best known for his works in the horror and fantasy genres.Open cnn.com (opens in a new tab)
Is the person primarily known for achievements in sports?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person primarily known for achievements in sports?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
Stephen (Edwin) King ... U.S. writer of horror stories ... one of the world’s best-selling writers.Open britannica.com (opens in a new tab)
Is the person primarily known for work in business or entrepreneurship?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person primarily known for work in business or entrepreneurship?"}}Oracle evidence2 model-reported sources
The Oracle reported these excerpts and URLs. They are not independently checked.
U.S. writer of horror stories... one of the world’s best-selling writers.Open britannica.com (opens in a new tab)
best-selling author Stephen King... best known for his works in the horror and fantasy genresOpen cnn.com (opens in a new tab)
Is the person primarily known as a writer or author?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person primarily known as a writer or author?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
U.S. writer of horror stories... one of the world’s best-selling writers.Open britannica.com (opens in a new tab)
Is the person primarily known for writing fiction?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person primarily known for writing fiction?"}}Oracle evidence2 model-reported sources
The Oracle reported these excerpts and URLs. They are not independently checked.
Stephen King is an American novelist and short-story writer whose books are credited with reviving the genre of horror fiction.Open britannica.com (opens in a new tab)
His acclaimed novels and short story collections include Carrie, The Shining, The Stand, Misery and 11.22.63.Open stephenkingbooks.co.uk (opens in a new tab)
Reply in the wrong format.
Invalid JSON · fixed format reminder sent
Why this reply was rejectedInvalid JSON · turn 12
The reply was not one complete, valid JSON object.
- Recorded type
invalid_json- Turn
- 12
- Counted
- Yes · question 12
- Feedback
- FORMAT_ERROR
{"result":{"action":"ASK","question":"Is the person primarily known as a novelist?","name":null,"description":null}}{"result":{"action":"ASK","question":"Is the person primarily known as a novelist?","name":null,"description":null}}{"result":{"action":"ASK","question":"Is the person primarily known as a novelist?","name":null,"description":null}}{"result":{"action":"ASK","question":"Is the person primarily known as a novelist?","name":null,"description":null}}{"result":{"action":"ASK","question":"Is the person American?","name":null,"description":null}}{"result":{"action":"ASK","description":null,"name":null,"question":"<non-empty yes-or-no property question>"}}{"result":{"action":"GUESS","description":"<non-empty identifying description>","name":"<non-empty candidate name>","question":null}} A reply must match one of these formats exactly. Text fields in use must not be empty; unused fields must be JSON null.
Is the person primarily known for writing novels?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person primarily known for writing novels?"}}Oracle evidence2 model-reported sources
The Oracle reported these excerpts and URLs. They are not independently checked.
Stephen King is a 'New York Times'-bestselling novelist who made his name in the horror and fantasy genres with books like 'Carrie,' 'The Shining' and 'IT.'Open biography.com (opens in a new tab)
His acclaimed novels and short story collections include Carrie, The Shining, The Stand, Misery and 11.22.63.Open stephenkingbooks.co.uk (opens in a new tab)
Is the person an American author?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Is the person an American author?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
Stephen Edwin King was born in Portland, Maine in 1947.Open stephenking.com (opens in a new tab)
Has the person written horror novels?
Recorded Guesser outputRequired JSON format
{"result":{"action":"ASK","description":null,"name":null,"question":"Has the person written horror novels?"}}Oracle evidence1 model-reported source
The Oracle reported these excerpts and URLs. They are not independently checked.
Stephen King is a 'New York Times'-bestselling novelist who made his name in the horror and fantasy genres with books like 'Carrie,' 'The Shining' and 'IT.'Open biography.com (opens in a new tab)
Stephen King
American author of horror novels such as It, The Shining, and Carrie
Validator rationale The proposed identity matches Stephen King, the American author associated with It, The Shining, and Carrie.
Recorded Guesser outputRequired JSON format
{"result":{"action":"GUESS","description":"American author of horror novels such as It, The Shining, and Carrie","name":"Stephen King","question":null}}