Model

Claude Opus 4.5

Test

N-Length Sentences

Scenario

Write sentences with 20 words each

Run ID

2026-02-08-01KGYX9GFYC37X5CV2B11TYW18

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 grandfather clock struck midnight when Detective Sarah Chen arrived at the sprawling Victorian mansion on Blackwood Hill Road. Rain pelted the windows like tiny fists demanding entry, and thunder rumbled ominously across the dark September sky above. She stepped inside the foyer where a butler stood waiting, his face pale as fresh fallen winter snow. The body of wealthy industrialist Marcus Webb lay crumpled at the bottom of the grand marble staircase near flowers. His eyes stared blankly at the crystal chandelier above, and a thin trail of blood pooled beneath his head. Three family members huddled in the adjacent parlor, each one watching the others with barely concealed suspicion and obvious fear. Sarah pulled out her notebook and pen, knowing that someone in this house had committed the ultimate unforgivable sin. The killer was close, perhaps standing mere feet away, waiting to see if their terrible secret would remain hidden.
created_at"2026-02-08T15:18:06.985244+00:00" Sunday, February 8th, 2026 at 3:18:06 PM GMT+00:00
model"anthropic/claude-4.5-opus-20251124" 
app_id182717
external_user(null)
streamedtrue
cancelledfalse
latency1838
moderation_latency(null)
generation_time7099
tokens_prompt35
tokens_completion182
native_tokens_prompt44
native_tokens_completion197
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" 
usage0.005145
router(null)
provider_responses
0
id"msg_019PEa8sKV35T8jRXK4CzC9d" 
status200
is_byokfalse
latency1838
endpoint_id"be883404-eb42-4b2d-b6e4-c7daa3aa8d62" 
provider_name"Anthropic" 
model_permaslug"anthropic/claude-4.5-opus-20251124" 
api_type"completions" 
id"gen-1770563879-IzIy0YRRJSnk8JP0hBwe" 
upstream_id"msg_019PEa8sKV35T8jRXK4CzC9d" 
total_cost0.005145
cache_discount(null)
upstream_inference_cost0
provider_name"Anthropic" 

Evaluation details

Result Evaluator Details Meta Data
59.6815% Matches word count n/a
neededCleanfalse
sentences8
wordCounts
019
119
218
319
419
520
619
719