NC Bench
Overview
About
Tests
Models
Model
Claude Opus 4.6
Test
N-Length Sentences
Scenario
Write sentences with 20 words each
Run ID
2026-02-08-01KGYYDD8WJZ2KE3WKV6F0TZSX
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 mansion stood at the end of Blackwood Lane, its windows dark and lifeless against the cold November sky. Detective Sarah Chen stepped out of her unmarked sedan and pulled her coat tighter against the bitter wind howling outside. A uniformed officer met her at the iron gate, his face pale and troubled beneath the flickering yellow porch light. "The body is in the study on the second floor, and I have to warn you that it is bad." She nodded without speaking and walked up the crumbling stone steps, her heels clicking sharply on each weathered gray surface. The front door hung open like a mouth frozen mid scream, revealing a grand foyer thick with dust and heavy shadows. A crystal chandelier swayed gently overhead, though no window was open and no breeze could possibly explain its strange subtle movement. She climbed the wide staircase and turned left down a hallway lined with portraits of the wealthy and long since dead. The study door was ajar, and warm golden light spilled across the dark oak floor like blood pooling from a wound. Inside, Professor Edward Holloway sat slumped at his mahogany desk, a single red rose placed carefully in his still right hand.
created_at
"2026-02-08T15:37:45.760874+00:00"
Sunday, February 8th, 2026 at 3:37:45 PM GMT+00:00
model
"anthropic/claude-4.6-opus-20260205"
app_id
182717
external_user
(null)
streamed
true
cancelled
false
latency
1787
moderation_latency
(null)
generation_time
9244
tokens_prompt
35
tokens_completion
238
native_tokens_prompt
44
native_tokens_completion
271
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
0.006995
router
(null)
provider_responses
0
id
"msg_01CJzoULbGpbXCu2awa38B3s"
status
200
is_byok
false
latency
1787
endpoint_id
"c926c048-563e-44b0-8434-95965bee924c"
provider_name
"Anthropic"
model_permaslug
"anthropic/claude-4.6-opus-20260205"
api_type
"completions"
id
"gen-1770565055-dIYA2Xf8GDuKt9uGSPtE"
upstream_id
"msg_01CJzoULbGpbXCu2awa38B3s"
total_cost
0.006995
cache_discount
(null)
upstream_inference_cost
0
provider_name
"Anthropic"
Evaluation details
Result
Evaluator
Details
Meta Data
80.3265%
Matches word count
n/a
neededClean
false
sentences
10
wordCounts
0
20
1
20
2
20
3
20
4
20
5
21
6
21
7
21
8
21
9
21