Model

Claude Opus 4.5

Test

N-Length Sentences

Scenario

Write sentences with 20 words each

Run ID

2026-02-08-01KGYY0QH2AYMMHKJK6DP5HG9H

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 old grandfather clock struck midnight as Detective Sarah Chen stepped into the dimly lit mansion on Blackwood Hill Road. Rain pattered against the tall windows while lightning illuminated the body sprawled across the expensive Persian rug in silence. Lord Edmund Blackwood lay face down with a silver letter opener protruding from between his shoulder blades at an angle. His right hand stretched toward the fireplace as if he had been reaching for something hidden within the flames. The butler stood trembling near the doorway with his face pale as fresh snow and his hands shaking quite visibly. Three guests remained in the drawing room nearby and each one refused to meet the detective's sharp and questioning gaze. Sarah knelt beside the corpse and noticed the dead man still clutched a torn photograph in his cold left hand. She carefully pried open his stiff fingers to reveal half an image showing a woman in a wedding dress. Someone in this house had secrets worth killing for and Sarah was determined to uncover every single buried truth tonight. The storm outside grew fiercer as she stood and turned to face the five suspects waiting in terrified silence.
created_at"2026-02-08T15:30:48.701777+00:00" Sunday, February 8th, 2026 at 3:30:48 PM GMT+00:00
model"anthropic/claude-4.5-opus-20251124" 
app_id182717
external_user(null)
streamedtrue
cancelledfalse
latency1485
moderation_latency(null)
generation_time7800
tokens_prompt35
tokens_completion219
native_tokens_prompt44
native_tokens_completion236
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" 
usage0.00612
router(null)
provider_responses
0
id"msg_01D2s4rSC6UUKtzozgtmCZD3" 
status200
is_byokfalse
latency1485
endpoint_id"be883404-eb42-4b2d-b6e4-c7daa3aa8d62" 
provider_name"Anthropic" 
model_permaslug"anthropic/claude-4.5-opus-20251124" 
api_type"completions" 
id"gen-1770564640-0332opu7NWfnXYLQCFPg" 
upstream_id"msg_01D2s4rSC6UUKtzozgtmCZD3" 
total_cost0.00612
cache_discount(null)
upstream_inference_cost0
provider_name"Anthropic" 

Evaluation details

Result Evaluator Details Meta Data
84.2612% Matches word count n/a
neededCleanfalse
sentences10
wordCounts
020
119
220
319
420
520
620
719
820
919