NC Bench
Overview
About
Tests
Models
Model
Claude Opus 4.5
Test
N-Length Sentences
Scenario
Write sentences with 20 words each
Run ID
2026-02-08-01KGYX45CVDPCX66BMQS2PCHP9
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 rain fell steadily on the cobblestone streets of Whitmore village as midnight approached the old abandoned textile mill nearby. Detective Sarah Chen stepped out of her vehicle and walked carefully toward the yellow police tape surrounding the scene. A body lay crumpled beneath the ancient oak tree where children had once played their innocent games so long ago. The victim was male, approximately forty years old, wearing an expensive suit that seemed entirely out of place around here. His eyes stared blankly at the stormy sky above while blood pooled beneath his head on the wet ground. Officer James Murphy approached her with a grim expression and handed over a small plastic evidence bag containing something peculiar. Inside was a single playing card, the queen of spades, with strange symbols drawn carefully in red ink on it. Sarah had seen this calling card before, exactly three years ago, when the Whitmore Strangler had terrorized this sleepy town. Everyone believed that killer was dead, buried in the cemetery on the hill after a dramatic confrontation with police. Now she wondered if they had caught the wrong person or if someone new was copying those terrible crimes precisely.
created_at
"2026-02-08T15:15:13.018275+00:00"
Sunday, February 8th, 2026 at 3:15:13 PM GMT+00:00
model
"anthropic/claude-4.5-opus-20251124"
app_id
182717
external_user
(null)
streamed
true
cancelled
false
latency
1480
moderation_latency
(null)
generation_time
8363
tokens_prompt
35
tokens_completion
225
native_tokens_prompt
44
native_tokens_completion
239
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
0.006195
router
(null)
provider_responses
0
id
"msg_014VFd8qhhHypDURTYGUnqs8"
status
200
is_byok
false
latency
1480
endpoint_id
"be883404-eb42-4b2d-b6e4-c7daa3aa8d62"
provider_name
"Anthropic"
model_permaslug
"anthropic/claude-4.5-opus-20251124"
api_type
"completions"
id
"gen-1770563704-I9N9VywNccVal6vLcCr9"
upstream_id
"msg_014VFd8qhhHypDURTYGUnqs8"
total_cost
0.006195
cache_discount
(null)
upstream_inference_cost
0
provider_name
"Anthropic"
Evaluation details
Result
Evaluator
Details
Meta Data
88.1959%
Matches word count
n/a
neededClean
false
sentences
10
wordCounts
0
20
1
19
2
20
3
20
4
19
5
20
6
20
7
20
8
19
9
20