Model

Claude Haiku 4.5

Test

N-Length Sentences

Scenario

Write sentences with 20 words each

Run ID

2026-02-08-01KGYZPSES8589BTTZR829YVM6

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 on the Library Floor Detective Sarah Chen arrived at Ashworth Manor just as the rain began falling heavily on the ancient grounds. Lord Ashworth lay sprawled across the Persian rug, a letter opener protruding from between his shoulder blades. His face was frozen in an expression of shock and surprise, suggesting the attack had been swift and totally unexpected. The butler, Mr. Graves, stood trembling in the doorway, wringing his hands as tears streamed down his weathered face. "He was alive just thirty minutes ago," Graves whispered hoarsely, his voice barely audible above the sound of the storm. Sarah knelt beside the body, careful not to disturb the crime scene with her coat or her steady hands. The letter opener bore the Ashworth family crest, suggesting the murderer had intimate knowledge of this house and its secrets. Through the library's tall windows, lightning illuminated the faces of three suspects who had all been present tonight. Lady Ashworth stood near the fireplace, her expression unreadable, while her nephew paced nervously near the bookshelf. The victim's business partner, Mr. Blackwood, sat rigidly in a leather chair, his knuckles white from gripping its wooden arms.
created_at"2026-02-08T16:00:15.761845+00:00" Sunday, February 8th, 2026 at 4:00:15 PM GMT+00:00
model"anthropic/claude-4.5-haiku-20251001" 
app_id182717
external_user(null)
streamedtrue
cancelledfalse
latency517
moderation_latency(null)
generation_time3229
tokens_prompt35
tokens_completion244
native_tokens_prompt44
native_tokens_completion272
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" 
usage0.001404
router(null)
provider_responses
0
id"msg_01QZCNa9fPkWX9LcTjgvnShC" 
status200
is_byokfalse
latency505
endpoint_id"41d2915a-92e6-4993-b537-210b4e10cba8" 
provider_name"Anthropic" 
model_permaslug"anthropic/claude-4.5-haiku-20251001" 
api_type"completions" 
id"gen-1770566411-thQu5r48Xbl8xvaHdH8h" 
upstream_id"msg_01QZCNa9fPkWX9LcTjgvnShC" 
total_cost0.001404
cache_discount(null)
upstream_inference_cost0
provider_name"Anthropic" 

Evaluation details

Result Evaluator Details Meta Data
50.0541% Matches word count n/a
neededCleanfalse
sentences11
wordCounts
07
118
217
320
419
520
619
720
818
917
1020