Model

Claude Haiku 4.5

Test

N-Length Sentences

Scenario

Write sentences with 20 words each

Run ID

2026-02-08-01KGYZKJCV0FMVB2R98CMDG6T6

Model input

User/Human
Please write the opening scene of a murder mystery where each sentence has exactly 20 words. Please make sure that each sentence has the same length. Only return the opening itself.

Model response

AI
# The Body in the Library The grandfather clock struck midnight as Detective Sarah Chen entered the sprawling Victorian mansion on Blackthorn Hill. Lord Edmund Ashworth lay motionless on the Persian rug, a silver letter opener protruding grotesquely from between his shoulder blades. His wife Margaret stood trembling near the fireplace, her face drained of color, mascara streaking down her porcelain cheeks. The study door had been locked from the inside when the screaming began, which complicated everything considerably. Outside, rain hammered against the tall windows as thunder rumbled across the Yorkshire moors in the distance. Sarah knelt beside the body, noting the still-warm skin and the peculiar smell of bitter almonds lingering in the air. Four suspects waited nervously in the drawing room: his son, his secretary, his estranged brother, and the housemaid. Each one had motive, opportunity, and secrets they desperately wanted to keep hidden from police scrutiny. Sarah stood slowly, her mind already cataloging inconsistencies in the stories she would soon hear from the assembled guests. The game, as they say in detective novels, was now afoot, and Edmund Ashworth would receive no earthly justice.
created_at"2026-02-08T15:58:31.427749+00:00" Sunday, February 8th, 2026 at 3:58:31 PM GMT+00:00
model"anthropic/claude-4.5-haiku-20251001" 
app_id182717
external_user(null)
streamedtrue
cancelledfalse
latency1396
moderation_latency(null)
generation_time4403
tokens_prompt35
tokens_completion234
native_tokens_prompt44
native_tokens_completion266
native_tokens_completion_images(null)
native_tokens_reasoning0
native_tokens_cached0
num_media_prompt(null)
num_input_audio_prompt(null)
num_media_completion0
num_search_results(null)
origin"https://ncbench.com/" 
is_byokfalse
finish_reason"stop" 
native_finish_reason"stop" 
usage0.001374
router(null)
provider_responses
0
id"msg_01Ve8PtBs3yvhMfURtBudw7J" 
status200
is_byokfalse
latency1396
endpoint_id"41d2915a-92e6-4993-b537-210b4e10cba8" 
provider_name"Anthropic" 
model_permaslug"anthropic/claude-4.5-haiku-20251001" 
api_type"completions" 
id"gen-1770566306-P3M0qP9I2FSTAJgVrqgD" 
upstream_id"msg_01Ve8PtBs3yvhMfURtBudw7J" 
total_cost0.001374
cache_discount(null)
upstream_inference_cost0
provider_name"Anthropic" 

Evaluation details

Result Evaluator Details Meta Data
32.6829% Matches word count n/a
neededCleanfalse
sentences11
wordCounts
06
117
220
319
417
517
621
718
816
919
1019