Grok 4.1 Fast - NC Bench

x-ai/grok-4.1-fast

Grok 4.1 Fast

via OpenRouter

Release Date

Nov 19th, 2025

Context Size

Reasoning

Yes

Benchmark Cost

$0.88

Speed

125.1 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	79	78	78	78	75	78%
Horror: alone in an eerie place at night Creative Writing Hallucination	89	83	83	79	78	82%
Literary fiction: old friends reunite Creative Writing Hallucination	88	85	85	85	82	85%
Mystery: examining a crime scene Creative Writing Hallucination	89	88	87	84	83	86%
Romance: separated couple reunites Creative Writing Hallucination	92	88	86	85	81	86%
Thriller: chase through city streets Creative Writing Hallucination	87	85	83	82	78	83%
Detailed Writing Rules						83.49%
genre
Fantasy: entering an ancient ruin Creative Writing Hallucination	76	76	76	74	72	75%
Horror: alone in an eerie place at night Creative Writing Hallucination	85	80	80	78	78	80%
Literary fiction: old friends reunite Creative Writing Hallucination	83	82	81	81	80	81%
Mystery: examining a crime scene Creative Writing Hallucination	84	83	80	79	75	80%
Romance: separated couple reunites Creative Writing Hallucination	82	80	80	77	76	79%
Thriller: chase through city streets Creative Writing Hallucination	83	81	80	76	73	79%
genre						79.05%
Novelcrafter Default Prompt
Fantasy: entering an ancient ruin Creative Writing Hallucination	82	81	78	77	74	78%
Horror: alone in an eerie place at night Creative Writing Hallucination	86	83	82	82	73	81%
Literary fiction: old friends reunite Creative Writing Hallucination	89	85	85	82	82	85%
Mystery: examining a crime scene Creative Writing Hallucination	84	83	80	79	78	81%
Romance: separated couple reunites Creative Writing Hallucination	83	81	80	80	79	81%
Thriller: chase through city streets Creative Writing Hallucination	85	85	85	85	84	85%
Novelcrafter Default Prompt						81.73%
81.43%

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	97	97	95	94	93	95%
Medium: The Hollow (Inferred) Tooling Reasoning	97	96	96	96	96	96%
Medium: Through the Thornveil (Scattered) Tooling Reasoning	99	98	98	98	97	98%
Short: The Rusty Lantern (Explicit) Tooling Reasoning	100	99	99	99	98	99%
97.12%

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	100	100	100	100	100	100	100	100	100	17	92%
Long text (~1594 words), small codex (11 entries) Hallucination	100	100	100	100	100	100	100	100	100	100	100%
Short text (~524 words), big codex (51 entries) Hallucination	100	100	100	100	100	100	100	100	100	100	100%
Short text (~524 words), small codex (11 entries) Hallucination	100	100	100	100	100	100	100	100	100	100	100%
basic entries											97.92%
detailed entries
Long text (~1594 words), big codex (51 detailed entries) Hallucination	100	100	100	100	100	100	100	100	100	100	100%
Long text (~1594 words), small codex (11 detailed entries) Hallucination	100	100	100	100	100	100	100	100	25	25	85%
Short text (~524 words), big codex (51 detailed entries) Hallucination	100	100	100	100	100	100	100	100	100	100	100%
Short text (~524 words), small codex (11 detailed entries) Hallucination	100	100	100	100	100	100	100	100	100	100	100%
detailed entries											96.25%
97.08%

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	100	99	98	97	97	95	95	94	90	90	95%
Large codex (40 entries), short passage (165 words) Tooling Reasoning	98	98	98	96	96	96	96	95	94	93	96%
Small codex (7 entries), long passage (734 words) Tooling Reasoning	100	100	97	95	95	92	92	88	87	79	93%
Small codex (7 entries), short passage (165 words) Tooling Reasoning	100	100	100	100	100	100	100	100	97	97	99%
matrix											95.84%
tiers
5 codex entries Tooling Reasoning	100	100	100	100	100	100	100	100	100	100	100%
10 codex entries Tooling Reasoning	100	100	100	100	100	100	100	100	100	100	100%
20 codex entries Tooling Reasoning	97	97	97	97	97	94	94	92	91	91	95%
40 codex entries Tooling Reasoning	100	100	100	100	100	100	100	100	100	100	100%
tiers											98.67%
97.25%

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	100	100	100	100	100	100	100	50	50	50	85%
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	50	50	50	50	80%
Indirect birth year Reasoning	100	100	100	100	100	100	100	100	100	100	100%
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%
What's the correct time? Reasoning	0	0	0	0	0	0	0	0	0	0	0%
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%
88.75%

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	50	50	47	47	41	38	38	38	34	48%
Write 200 words with 50% dialogue Rule Following Utility	98	94	81	69	64	60	53	50	50	3	62%
Write 200 words with 90% dialogue Rule Following Utility	99	93	85	82	72	66	64	53	51	29	69%
dialogue-200											59.91%
dialogue-500
Write 500 words with 30% dialogue Rule Following Utility	48	22	2	0	0	0	0	0	0	0	7%
Write 500 words with 50% dialogue Rule Following Utility	38	1	0	0	0	0	0	0	0	0	4%
Write 500 words with 70% dialogue Rule Following Utility	80	48	41	38	31	27	25	15	7	3	31%
dialogue-500											14.15%
Ungrouped
Write unattributed dialogue Rule Following	100	100	100	100	100	100	100	100	100	100	100%
46.02%

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	0	0	60%
Friend got new kittens (German) Language	100	100	100	100	100	100%
Friend got new kittens (Tagalog) Language	100	100	100	100	100	100%
90.00%

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	78	96%
Character dialogue (German) in a story Language	100	100	100	100	92	98%
Character dialogue (Hindi) in a story Language	56	56	50	50	45	51%
Character dialogue (Italian) in a story Language	100	100	100	100	80	96%
Character dialogue (Spanish) in a story Language	100	100	100	100	82	96%
87.51%

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	100	99	91	80	78	78	78	78	78	78	84%
Write sentences with 10 words each Utility	100	100	97	94	92	91	87	85	84	82	91%
Write sentences with 20 words each Utility	100	95	85	21	19	15	2	0	0	0	34%
69.57%

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	50	50	50	50	50	50	50	0	0	0	35%
Count point of views for Jack Harper Utility	100	100	100	100	100	100	100	100	100	0	90%
Count point of views for Olivia Utility	100	100	100	100	100	100	100	100	0	0	80%
pov-count											68.33%
84.17%

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	100	100	97	97	97	93	83	95%
Expand all contractions Text Editing	100	100	100	100	100	100	67	95%
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	96	96	96	95	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	100	99	97	93	89	88	88	93%
Generic Prompt								97.80%
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	100	100	99	99	99	99	99	100%
Expand all contractions Text Editing	100	100	100	99	99	99	98	99%
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	95	99%
Passive voice → active voice Text Editing Hallucination	99	99	98	98	97	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	99	99	99	96	99%
Specific Prompt								99.51%
98.66%

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	0	0	0	0	60%
Simple Rule Following	100	100	100	100	100	100	100	100	0	0	80%
Simple (1-shot) 1-shot Rule Following	100	100	100	100	100	100	100	100	0	0	80%
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%
84.00%

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	100	100	100	100	100	100	100	54	27	88%
50 sentence summary Utility	100	100	100	100	100	100	100	100	100	0	90%
sentences											95.61%
words
10 word summary Utility	100	100	100	100	100	100	100	100	100	100	100%
20 word summary Utility	100	100	100	100	100	100	100	98	98	98	100%
50 word summary Utility	100	100	100	100	100	100	98	98	92	2	89%
100 word summary Utility	92	77	54	54	54	0	0	0	0	0	33%
200 word summary Utility	100	9	2	0	0	0	0	0	0	0	11%
words											66.54%
85.44%