NC Bench
Overview
About
Tests
Categories
Models
Vendors
Compare
Run: 2026-05-29-01KSSJXSWJWXR53KMJJ83PE7YE
Run Details
Model:
Claude Opus 4.8 (Reasoning)
Test:
N-Length Sentences
Scenario:
Write sentences with 20 words each
Duration:
17.5s
Cost:
$0.046550
Provider:
Anthropic
Evaluation summary
Score
Evaluator
Details Link
100.00%
Matches word count
(details)
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 cold rain fell hard against the old mansion windows, washing away the dark secrets that lived inside its walls. Detective Sarah Morgan stepped slowly through the heavy front door, her flashlight cutting across the silent, shadowed grand entrance hall. On the cold marble floor lay a man, his eyes wide open, a crimson stain spreading beneath his crumpled body. She knelt down beside the victim carefully, noting the broken glass, the spilled wine, and the single muddy footprint nearby. Upstairs, a single floorboard creaked softly, reminding her that someone else still lurked within this house of buried, deadly lies.
created_at
"2026-05-29T10:01:54.33Z"
5/29/2026, 10:01:54 AM
model
"anthropic/claude-4.8-opus-20260528"
app_id
182717
external_user
(null)
streamed
true
cancelled
false
latency
3649
moderation_latency
(null)
generation_time
17464
tokens_prompt
46
tokens_completion
294
native_tokens_prompt
60
native_tokens_completion
1850
native_tokens_completion_images
(null)
native_tokens_reasoning
131
native_tokens_cached
0
num_media_prompt
(null)
num_input_audio_prompt
(null)
num_media_completion
0
num_search_results
(null)
num_fetches
(null)
web_search_engine
(null)
origin
"https://ncbench.com/"
is_byok
false
finish_reason
"stop"
native_finish_reason
"end_turn"
service_tier
"default"
usage
0.04655
router
(null)
provider_responses
0
endpoint_id
"b0d3beaa-5ff7-4666-a749-b1bb2b14c916"
id
"msg_01H71KD45URUYE8vohXoQNqC"
is_byok
false
latency
1098
model_permaslug
"anthropic/claude-4.8-opus-20260528"
provider_name
"Anthropic"
status
200
user_agent
"langchainjs-openai/1.0.0 ((node/v24.16.0; linux; x64))"
http_referer
(null)
request_id
"req-1780048914-hQVDdaaY1L2x7yXWt9hA"
session_id
(null)
api_type
"completions"
id
"gen-1780048914-9kgtipjppZtiaBe0mxB0"
upstream_id
"msg_01H71KD45URUYE8vohXoQNqC"
total_cost
0.04655
cache_discount
(null)
upstream_inference_cost
0
provider_name
"Anthropic"
response_cache_source_id
(null)
Evaluation details
Result
Evaluator
Details
Meta Data
100.00%
Matches word count
n/a
neededClean
false
sentences
5
wordCounts
0
20
1
20
2
20
3
20
4
20