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Run: 2026-05-29-01KSSJEWTMB6C41VFZ506R3N0T
Run Details
Model:
Claude Opus 4.8 (Reasoning)
Test:
N-Length Sentences
Scenario:
Write sentences with 20 words each
Duration:
27.8s
Cost:
$0.076100
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 rain hammered against the old mansion windows as Detective Sarah Cole stepped slowly through the creaking rusted iron gate. Inside the dimly lit foyer, a single chandelier flickered weakly above the lifeless body sprawled across the cold marble floor. The victim, wealthy industrialist Marcus Thorne, lay completely motionless with one hand still clutching a torn fragment of yellowed paper. Sarah knelt down beside him, carefully studying the strange symbol drawn in crimson ink across his pale, frozen left cheek. Footsteps echoed somewhere far upstairs, and she suddenly froze, realizing the killer might still be hiding within these shadowed walls. Gripping her flashlight tightly, Sarah slowly rose to her feet and began climbing the grand, creaking staircase toward certain danger.
created_at
"2026-05-29T09:53:45.823Z"
5/29/2026, 9:53:45 AM
model
"anthropic/claude-4.8-opus-20260528"
app_id
182717
external_user
(null)
streamed
true
cancelled
false
latency
4222
moderation_latency
(null)
generation_time
27777
tokens_prompt
46
tokens_completion
414
native_tokens_prompt
60
native_tokens_completion
3032
native_tokens_completion_images
(null)
native_tokens_reasoning
207
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
0.0761
router
(null)
provider_responses
0
endpoint_id
"b0d3beaa-5ff7-4666-a749-b1bb2b14c916"
id
"msg_01YZ5K8vAfaLQkuze75sBAFL"
is_byok
false
latency
2068
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-1780048425-QTjExrOYlOz97gjz2sVi"
session_id
(null)
api_type
"completions"
id
"gen-1780048425-EbBW7VbWsQBfS2eM2ZFR"
upstream_id
"msg_01YZ5K8vAfaLQkuze75sBAFL"
total_cost
0.0761
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
6
wordCounts
0
20
1
20
2
20
3
20
4
20
5
20