NC Bench
Overview
About
Tests
Models
Model
Claude Opus 4.5
Test
N-Length Sentences
Scenario
Write sentences with 20 words each
Run ID
2026-02-08-01KGYZA1MJ3VCD3RBN4N0HMNVN
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
Messages
Meta
AI
The old grandfather clock struck midnight precisely as Detective Sarah Chen arrived at the sprawling Victorian mansion on Blackwood Hill. Rain pelted the windows with furious intensity while thunder rumbled ominously in the distance like some ancient beast awakening slowly. She stepped inside the foyer and immediately noticed the body sprawled across the marble floor near the grand staircase. Lord William Ashworth lay motionless in a pool of dark crimson blood, his eyes frozen open in eternal silent terror. A crystal champagne glass rested shattered beside his outstretched hand, its contents now mingling grotesquely with the spreading red stain. The butler stood trembling in the corner, his face ashen white, unable to tear his horrified gaze from his master. Five dinner guests remained gathered in the adjacent parlor room, each one wearing expressions that mixed shock with something else. Sarah knelt beside the body and examined the small puncture wound visible just below the victim's left ear with care. This was no accident and certainly no suicide; someone in this house tonight had committed a cold and calculated murder. She rose slowly to her feet and turned to face the assembled suspects who waited nervously for her next words.
created_at
"2026-02-08T15:53:23.237071+00:00"
Sunday, February 8th, 2026 at 3:53:23 PM GMT+00:00
model
"anthropic/claude-4.5-opus-20251124"
app_id
182717
external_user
(null)
streamed
true
cancelled
false
latency
1749
moderation_latency
(null)
generation_time
8219
tokens_prompt
35
tokens_completion
236
native_tokens_prompt
44
native_tokens_completion
265
native_tokens_completion_images
(null)
native_tokens_reasoning
0
native_tokens_cached
0
num_media_prompt
(null)
num_input_audio_prompt
(null)
num_media_completion
0
num_search_results
(null)
origin
"https://ncbench.com/"
is_byok
false
finish_reason
"stop"
native_finish_reason
"stop"
usage
0.006845
router
(null)
provider_responses
0
id
"msg_01GApApRP8tsXwhkHsvFTCVr"
status
200
is_byok
false
latency
1749
endpoint_id
"be883404-eb42-4b2d-b6e4-c7daa3aa8d62"
provider_name
"Anthropic"
model_permaslug
"anthropic/claude-4.5-opus-20251124"
api_type
"completions"
id
"gen-1770565994-lAhLQ87DGvodBdihMy3y"
upstream_id
"msg_01GApApRP8tsXwhkHsvFTCVr"
total_cost
0.006845
cache_discount
(null)
upstream_inference_cost
0
provider_name
"Anthropic"
Evaluation details
Result
Evaluator
Details
Meta Data
96.0653%
Matches word count
n/a
neededClean
false
sentences
10
wordCounts
0
20
1
20
2
19
3
20
4
20
5
20
6
20
7
20
8
20
9
20