Claude Sonnet 5 - NC Bench

anthropic/claude-sonnet-5

Claude Sonnet 5

via OpenRouter

Release Date

Jun 30th, 2026

Context Size

Reasoning

Benchmark Cost

$10.88

Speed

56.4 tok/s

Subcategories

Bad Writing Habits

Detects common prose quality anti-patterns in AI-generated creative writing, including passive voice, past progressive overuse, weak dialogue tags, filter words, purple prose, cliches, AI-ism words/adverbs/names, and more.

Scenario	#1	#2	#3	#4	#5	Total
Detailed Writing Rules
Fantasy: entering an ancient ruin Creative Writing Hallucination	84	82	82	82	81	82%
Horror: alone in an eerie place at night Creative Writing Hallucination	92	92	88	85	84	88%
Literary fiction: old friends reunite Creative Writing Hallucination	86	86	86	83	82	85%
Mystery: examining a crime scene Creative Writing Hallucination	95	91	87	86	82	88%
Romance: separated couple reunites Creative Writing Hallucination	85	81	80	77	75	79%
Thriller: chase through city streets Creative Writing Hallucination	94	92	89	88	82	89%
Detailed Writing Rules						85.28%
genre
Fantasy: entering an ancient ruin Creative Writing Hallucination	83	78	76	70	67	75%
Horror: alone in an eerie place at night Creative Writing Hallucination	90	85	83	80	79	83%
Literary fiction: old friends reunite Creative Writing Hallucination	76	76	73	71	70	73%
Mystery: examining a crime scene Creative Writing Hallucination	83	83	83	81	81	82%
Romance: separated couple reunites Creative Writing Hallucination	75	74	74	73	73	74%
Thriller: chase through city streets Creative Writing Hallucination	87	86	80	79	76	82%
genre						78.20%
Novelcrafter Default Prompt
Fantasy: entering an ancient ruin Creative Writing Hallucination	81	78	78	77	76	78%
Horror: alone in an eerie place at night Creative Writing Hallucination	90	82	82	81	75	82%
Literary fiction: old friends reunite Creative Writing Hallucination	84	84	83	79	76	81%
Mystery: examining a crime scene Creative Writing Hallucination	92	88	86	85	85	87%
Romance: separated couple reunites Creative Writing Hallucination	82	81	80	80	74	80%
Thriller: chase through city streets Creative Writing Hallucination	89	86	85	85	81	85%
Novelcrafter Default Prompt						82.23%
81.90%

Codex Extraction

Evaluates a model's ability to extract structured codex entries (characters, locations, objects, lore) from prose passages and return them as well-formed XML.

Scenario	#1	#2	#3	#4	#5	Total
Long: The Spire of Echoes (Dense) Tooling Reasoning	98	97	97	97	95	97%
Medium: The Hollow (Inferred) Tooling Reasoning	98	97	97	97	97	97%
Medium: Through the Thornveil (Scattered) Tooling Reasoning	99	99	99	98	98	99%
Short: The Rusty Lantern (Explicit) Tooling Reasoning	99	98	98	94	94	97%
97.33%

Codex Red Herring (False Positive Detection)

Tests whether models correctly report "no violations" when a codex is fully consistent with the prose passage. Models that hallucinate false violations (false positives) fail. Uses a 2×2 matrix of text length × codex size, with bare and detailed-entry variants.

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
basic entries
Long text (~1594 words), big codex (51 entries) Hallucination	35	35	33	33	33	33	32	32	8	8	28%
Long text (~1594 words), small codex (11 entries) Hallucination	42	38	35	33	33	32	13	10	10	7	25%
Short text (~524 words), big codex (51 entries) Hallucination	42	25	25	25	25	25	25	25	25	25	27%
Short text (~524 words), small codex (11 entries) Hallucination	25	25	25	25	25	25	25	25	25	25	25%
basic entries											26.34%
detailed entries
Long text (~1594 words), big codex (51 detailed entries) Hallucination	38	38	35	33	33	33	33	13	10	8	27%
Long text (~1594 words), small codex (11 detailed entries) Hallucination	35	35	33	33	33	33	32	10	8	8	26%
Short text (~524 words), big codex (51 detailed entries) Hallucination	42	38	35	25	17	13	13	13	13	8	21%
Short text (~524 words), small codex (11 detailed entries) Hallucination	100	100	100	100	100	100	100	100	100	100	100%
detailed entries											43.76%
35.05%

Codex Violation Detection

Detects factual inconsistencies between a story bible and prose passages. The model must output structured XML identifying each violation with paragraph number and substring.

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
matrix
Large codex (40 entries), long passage (1,019 words) Tooling Reasoning	90	90	87	86	86	85	84	63	60	3	73%
Large codex (40 entries), short passage (165 words) Tooling Reasoning	96	92	91	91	87	85	83	74	74	74	85%
Small codex (7 entries), long passage (734 words) Tooling Reasoning	91	88	83	83	80	80	75	75	3	3	66%
Small codex (7 entries), short passage (165 words) Tooling Reasoning	100	100	100	100	97	97	97	97	97	97	98%
matrix											80.58%
tiers
5 codex entries Tooling Reasoning	91	91	91	91	91	91	91	91	91	91	91%
10 codex entries Tooling Reasoning	100	100	100	100	100	100	100	100	100	72	97%
20 codex entries Tooling Reasoning	100	97	89	85	76	52	33	3	3	3	54%
40 codex entries Tooling Reasoning	100	100	100	97	92	88	83	82	77	77	89%
tiers											83.00%
81.79%

Data extraction

Extract key details from a given block of text.

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
All valid emails Utility	100	100	100	100	100	100	100	100	100	100	100%
Contextual pronoun Utility	100	100	100	100	100	100	100	100	100	100	100%
Fruits excluding citrus Utility	100	100	100	100	100	100	100	100	100	100	100%
Future event time Reasoning	50	50	50	50	50	50	50	50	50	50	50%
Guess the pet Reasoning	100	100	100	100	100	100	100	100	100	100	100%
Highest-rated movie Reasoning	100	100	100	100	100	100	100	100	100	100	100%
Indirect birth year Reasoning	100	100	100	50	50	50	50	50	50	50	65%
What instrument does Lucy play? Reasoning	100	100	100	100	100	100	100	100	100	100	100%
What's the color of the car? Utility	100	100	100	100	100	100	100	100	100	100	100%
Who's the sister? Reasoning	100	100	100	100	100	100	100	100	100	100	100%
Who's the tallest? Reasoning	100	100	100	100	100	100	100	100	100	100	100%
92.27%

Dialogue tags

Various tasks related to dialogue tags in text.

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
dialogue-200
Write 200 words with 10% dialogue Rule Following Utility	100	65	64	60	53	50	49	47	47	16	55%
Write 200 words with 50% dialogue Rule Following Utility	50	50	50	49	49	49	49	41	34	30	45%
Write 200 words with 90% dialogue Rule Following Utility	100	99	99	91	84	75	75	60	59	47	79%
dialogue-200											59.79%
dialogue-500
Write 500 words with 30% dialogue Rule Following Utility	50	50	50	49	41	34	34	18	0	0	33%
Write 500 words with 50% dialogue Rule Following Utility	51	50	50	41	34	30	18	5	3	0	28%
Write 500 words with 70% dialogue Rule Following Utility	94	88	87	83	74	71	64	58	50	1	67%
dialogue-500											42.57%
Ungrouped
Write unattributed dialogue Rule Following	100	100	100	100	100	100	100	100	100	100	100%
58.15%

Language Comprehension

Does the model understand more than just English?

Scenario	#1	#2	#3	#4	#5	Total
Asking for directions (Dutch) Language	100	100	100	100	100	100%
Asking for directions (German) Language	100	100	100	100	0	80%
Friend got new kittens (German) Language	100	100	100	100	100	100%
Friend got new kittens (Tagalog) Language	100	100	100	100	100	100%
95.00%

Language Writing

Can the model generate text in different languages?

Scenario	#1	#2	#3	#4	#5	Total
Character dialogue (French) in a story Language	100	100	100	100	100	100%
Character dialogue (German) in a story Language	100	100	100	100	100	100%
Character dialogue (Hindi) in a story Language	100	100	100	50	50	80%
Character dialogue (Italian) in a story Language	100	100	100	100	100	100%
Character dialogue (Spanish) in a story Language	100	100	100	100	100	100%
96.00%

N-Length Sentences

Write sentences with exactly N words

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
Write sentences with 5 words each Utility	99	95	93	90	90	88	87	83	80	75	88%
Write sentences with 10 words each Utility	70	70	68	67	64	63	46	45	42	30	57%
Write sentences with 20 words each Utility	0	0	0	0	0	0	0	0	0	0	0%
48.20%

Novel outline

Handle questions about the outline of a novel in various formats

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
outline-count
Count acts Utility	100	100	100	100	100	100	100	100	100	100	100%
Count chapters Utility	100	100	100	100	100	100	100	100	100	100	100%
Count scenes Utility	100	100	100	100	100	100	100	100	100	100	100%
outline-count											100.00%
pov-count
Count point of views for Jack and Olivia Utility	100	100	100	100	100	100	100	100	100	100	100%
Count point of views for Jack Harper Utility	100	100	100	100	100	100	100	100	100	100	100%
Count point of views for Olivia Utility	100	100	100	100	100	100	100	100	100	0	90%
pov-count											96.67%
98.33%

Relationship tree

Extracts a deterministic XML family and relationship tree from cumulative literary prose.

Scenario	#1	#2	#3	#4	#5	Total
Core relationship tree Tooling Reasoning Hallucination	84	82	80	80	76	80%
Family relationship tree Tooling Reasoning Hallucination	78	74	74	73	69	73%
76.87%

Text Replacement

Tests deterministic text transformations: renaming characters/locations, expanding contractions, tense rewriting, POV shifts, gender swaps, combined transformations, and word avoidance. Scored by checking each expected change independently.

Scenario	#1	#2	#3	#4	#5	#6	#7	Total
Generic Prompt
Avoid said/asked/replied/answered Text Editing	100	100	100	100	100	100	100	100%
Character rename: Elena->Mirabel, Gregor->Aldric Text Editing	100	100	100	100	100	100	100	100%
Combined: 3rd person past → 1st person present Text Editing	99	99	99	99	99	99	99	99%
Expand all contractions Text Editing	100	100	100	100	100	100	100	100%
Location rename: market square, outer ring, bridge, northern mines Text Editing	100	100	100	100	96	96	96	98%
Multi-character gender swap: Priya(F)->Rohan(M), Mara unchanged Text Editing	100	100	100	100	100	100	100	100%
Passive voice → active voice Text Editing Hallucination	98	98	97	96	94	94	93	96%
POV shift: 3rd person to 1st person (Elena's perspective) Text Editing	100	100	100	100	100	100	100	100%
Tense rewriting: past to present Text Editing	99	99	99	99	99	99	99	99%
Generic Prompt								99.05%
Specific Prompt
Avoid said/asked/replied/answered Text Editing	100	100	100	100	100	100	100	100%
Character rename: Elena->Mirabel, Gregor->Aldric Text Editing	100	100	100	100	100	100	100	100%
Combined: 3rd person past → 1st person present Text Editing	99	99	99	99	98	98	98	99%
Expand all contractions Text Editing	100	100	100	100	100	100	99	100%
Location rename: market square, outer ring, bridge, northern mines Text Editing	100	100	100	100	100	100	100	100%
Multi-character gender swap: Priya(F)->Rohan(M), Mara unchanged Text Editing	100	100	100	100	100	100	100	100%
Passive voice → active voice Text Editing Hallucination	98	98	98	98	98	97	97	98%
POV shift: 3rd person to 1st person (Elena's perspective) Text Editing	100	100	100	100	100	100	100	100%
Tense rewriting: past to present Text Editing	100	100	100	100	99	99	99	100%
Specific Prompt								99.56%
99.31%

Tool usage within Novelcrafter

Output messages that are related to tool usage within Novelcrafter

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
Create alternate prose sections Tooling	100	100	100	100	100	100	100	100	100	100	100%
100.00%

Voice/dialogue sheets

Extract dialogue from given text as voice sheets.

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
Multiple speakers Rule Following	100	100	100	100	100	100	100	100	100	0	90%
Simple Rule Following	100	100	100	100	100	100	100	100	100	100	100%
Simple (1-shot) 1-shot Rule Following	100	100	100	100	100	100	100	100	100	100	100%
Simple (5-shot) Few-shot Rule Following	100	100	100	100	100	100	100	100	100	100	100%
Unattributed dialogue Rule Following	100	100	100	100	100	100	100	100	100	100	100%
98.00%

Write N of X

Write exactly N words/sentences/paragraphs...

Scenario	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	Total
paragraphs
1 paragraph summary Utility	100	100	100	100	100	100	100	100	100	100	100%
3 paragraph summary Utility	100	100	100	100	100	100	100	100	100	100	100%
5 paragraph summary Utility	100	100	100	100	100	100	100	100	100	100	100%
paragraphs											100.00%
sentences
1 sentence summary Utility	100	100	100	100	100	100	100	100	100	100	100%
3 sentence summary Utility	100	100	100	100	100	100	100	100	100	100	100%
10 sentence summary Utility	100	100	100	100	100	100	100	100	100	100	100%
20 sentence summary Utility	100	92	92	77	77	77	77	54	54	54	75%
50 sentence summary Utility	92	92	92	77	77	54	2	0	0	0	49%
sentences											84.82%
words
10 word summary Utility	100	100	98	98	98	98	98	98	92	92	97%
20 word summary Utility	100	92	92	92	77	77	77	54	27	2	69%
50 word summary Utility	9	9	2	2	2	0	0	0	0	0	2%
100 word summary Utility	100	92	77	77	54	54	27	27	27	2	54%
200 word summary Utility	100	100	98	27	9	9	9	0	0	0	35%
words											51.60%
75.55%