Model

Claude Opus 4.5

Test

N-Length Sentences

Scenario

Write sentences with 20 words each

Run ID

2026-02-08-01KGYY1G87FGN807YGRFMXEXET

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 as Detective Sarah Chen stepped into the abandoned mansion on Blackwood Hill last night. Rain pelted the broken windows while thunder rumbled ominously across the dark sky, creating an atmosphere of pure dread. A body lay sprawled across the marble floor, one hand reaching toward the locked door in frozen desperate terror. The victim was wealthy businessman Harold Crane, found by his terrified housekeeper who had heard strange noises around eleven. Blood pooled beneath his expensive silk shirt, and his eyes stared blankly at the crystal chandelier hanging far above. Sarah knelt beside the corpse, noting the unusual wound pattern that suggested this was no ordinary robbery gone terribly wrong. Her partner Detective Marcus Webb arrived moments later, shaking water from his coat as he surveyed the grim crime scene. No signs of forced entry anywhere in the house meant the killer either had a key or was invited inside. The housekeeper mentioned that Crane had been expecting an important visitor, but she never saw anyone actually enter the mansion. Sarah noticed a torn piece of expensive fabric clutched tightly in the dead man's rigid fist, perhaps from his attacker.
created_at"2026-02-08T15:31:13.521426+00:00" Sunday, February 8th, 2026 at 3:31:13 PM GMT+00:00
model"anthropic/claude-4.5-opus-20251124" 
app_id182717
external_user(null)
streamedtrue
cancelledfalse
latency1567
moderation_latency163
generation_time7088
tokens_prompt35
tokens_completion226
native_tokens_prompt44
native_tokens_completion257
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" 
usage0.006645
router(null)
provider_responses
0
id"2e1edca4-004e-4baa-9a6f-bdb9944617a8" 
status200
is_byokfalse
latency1567
endpoint_id"de32581c-2e11-4f54-8d29-e8a6e19d3038" 
provider_name"Amazon Bedrock" 
model_permaslug"anthropic/claude-4.5-opus-20251124" 
api_type"completions" 
id"gen-1770564665-Dq5dyFmtkavp61PS6qpS" 
upstream_id"2e1edca4-004e-4baa-9a6f-bdb9944617a8" 
total_cost0.006645
cache_discount(null)
upstream_inference_cost0
provider_name"Amazon Bedrock" 

Evaluation details

Result Evaluator Details Meta Data
80.3265% Matches word count n/a
neededCleanfalse
sentences10
wordCounts
019
119
219
319
419
520
620
720
820
920