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Run: 2026-09-23-01M37Q8NYB8WF4JW4NE7Y1XHJB
Run Details
Model:
Claude Opus 5.5 (Reasoning)
Test:
N-Length Sentences
Scenario:
Write sentences with 20 words each
Duration:
20.6s
Cost:
$0.040448
Provider:
Claude Platform on AWS
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 storm had been raging for three days when Lady Margaret Ashworth was found dead in the old locked library. Inspector Thomas Reed stood in the doorway, rainwater dripping from his coat, and studied the scene with tired grey eyes. She lay slumped across the mahogany desk, one hand clutching a silver fountain pen, the other dangling toward the floor. The only key to the room had been discovered beneath her body, which made the whole situation considerably more troubling. Behind him, the butler cleared his throat nervously and announced that the other guests were waiting in the drawing room. Reed nodded slowly, knowing that one of those five elegant strangers had almost certainly committed this murder sometime last night. Before he joined them, he noticed something strange: the clock on the mantelpiece had stopped at eleven minutes past midnight. Somebody in this house was lying, and Reed intended to discover who before the storm cleared and they finally escaped.
created_at
"2026-09-23T18:08:23.514Z"
9/23/2026, 6:08:23 PM
model
"anthropic/claude-opus-5.5-20260921"
app_id
182717
external_user
(null)
streamed
true
cancelled
false
latency
5053
moderation_latency
(null)
generation_time
20513
tokens_prompt
46
tokens_completion
571
native_tokens_prompt
62
native_tokens_completion
2010
native_tokens_completion_images
(null)
native_tokens_reasoning
1700
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
0.040448
router
(null)
user_agent
"langchainjs-openai/1.0.0 ((node/v24.20.0; linux; x64))"
http_referer
(null)
request_id
"req-1790186903-EdlZxsxsQLU1rMNcCbPy"
session_id
(null)
preset_id
(null)
api_type
"completions"
id
"gen-1790186903-RDQu2fpplul8jW563jVl"
upstream_id
"msg_011CfLpQcpbD9xkHb6dCCRJ8"
provider_responses
0
endpoint_id
"3a2388bc-3740-4e64-a1f5-4e301726b6b9"
id
"msg_011CfLpQcpbD9xkHb6dCCRJ8"
is_byok
false
latency
1200
model_permaslug
"anthropic/claude-opus-5.5-20260921"
provider_name
"Claude Platform on AWS"
status
200
total_cost
0.040448
cache_discount
(null)
upstream_inference_cost
0
provider_name
"Claude Platform on AWS"
response_cache_source_id
(null)
data_region
"global"
workspace_id
"97e315e5-d303-487d-83c1-83180e8a13d4"
Evaluation details
Result
Evaluator
Details
Meta Data
100.00%
Matches word count
n/a
neededClean
false
sentences
8
wordCounts
0
20
1
20
2
20
3
20
4
20
5
20
6
20
7
20