Grok 4.20 (Reasoning)

x-ai/grok-4.20

Grok 4.20 (Reasoning)

via OpenRouter

Release Date

Mar 31st, 2026

Context Size

Reasoning

Yes

Benchmark Cost

$9.06

Speed

93.4 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	88	86	84	84	80	84%
Horror: alone in an eerie place at night Creative Writing Hallucination	92	86	83	82	82	85%
Literary fiction: old friends reunite Creative Writing Hallucination	90	88	88	88	87	88%
Mystery: examining a crime scene Creative Writing Hallucination	92	87	87	84	80	86%
Romance: separated couple reunites Creative Writing Hallucination	91	89	89	85	82	87%
Thriller: chase through city streets Creative Writing Hallucination	89	89	88	83	82	86%
Detailed Writing Rules						86.19%
genre
Fantasy: entering an ancient ruin Creative Writing Hallucination	86	83	79	78	74	80%
Horror: alone in an eerie place at night Creative Writing Hallucination	82	81	80	79	77	80%
Literary fiction: old friends reunite Creative Writing Hallucination	88	86	85	83	80	85%
Mystery: examining a crime scene Creative Writing Hallucination	88	86	81	79	76	82%
Romance: separated couple reunites Creative Writing Hallucination	85	83	82	78	76	81%
Thriller: chase through city streets Creative Writing Hallucination	84	83	78	69	63	75%
genre						80.48%
Novelcrafter Default Prompt
Fantasy: entering an ancient ruin Creative Writing Hallucination	89	89	88	85	85	87%
Horror: alone in an eerie place at night Creative Writing Hallucination	89	86	85	84	84	86%
Literary fiction: old friends reunite Creative Writing Hallucination	96	96	95	94	90	94%
Mystery: examining a crime scene Creative Writing Hallucination	98	92	92	90	89	92%
Romance: separated couple reunites Creative Writing Hallucination	90	87	87	85	83	86%
Thriller: chase through city streets Creative Writing Hallucination	91	91	90	89	89	90%
Novelcrafter Default Prompt						89.32%
85.33%

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	96	97%
Medium: The Hollow (Inferred) Tooling Reasoning	99	98	98	98	97	98%
Medium: Through the Thornveil (Scattered) Tooling Reasoning	98	98	98	98	96	98%
Short: The Rusty Lantern (Explicit) Tooling Reasoning	100	100	98	98	98	99%
97.83%

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	17	17	17	17	17	17	50%
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											87.50%
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	100	25	93%
Short text (~524 words), big codex (51 detailed entries) Hallucination	100	100	100	100	100	25	25	25	17	17	61%
Short text (~524 words), small codex (11 detailed entries) Hallucination	100	100	100	100	100	100	100	100	100	25	93%
detailed entries											86.46%
86.98%

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	99	98	98	97	97	96	96	94	98%
Large codex (40 entries), short passage (165 words) Tooling Reasoning	98	98	98	98	96	96	96	96	96	95	97%
Small codex (7 entries), long passage (734 words) Tooling Reasoning	100	100	100	100	95	95	95	95	95	95	97%
Small codex (7 entries), short passage (165 words) Tooling Reasoning	100	100	100	100	100	100	100	100	100	97	100%
matrix											97.84%
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	92	92	92	92	97%
20 codex entries Tooling Reasoning	100	97	97	97	97	97	97	94	94	94	96%
40 codex entries Tooling Reasoning	100	100	100	100	100	100	100	100	100	100	100%
tiers											98.34%
98.09%

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	50	50	50	50	50	50	50	50	50	50	50%
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	50	50	50	50	50	50	50	50	60%
Highest-rated movie Reasoning	100	100	100	100	100	50	50	50	50	50	75%
Indirect birth year Reasoning	100	100	100	100	100	100	100	100	50	50	90%
What instrument does Lucy play? Reasoning	100	100	50	50	50	50	50	50	50	50	60%
What's the color of the car? Utility	100	100	100	100	50	50	50	50	50	50	70%
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	50	50	50	50	80%
Who's the tallest? Reasoning	100	100	50	50	50	50	50	50	50	50	60%
66.25%

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	100	100	100	100	100	99	95	93	84	97%
Write 200 words with 50% dialogue Rule Following Utility	100	100	98	98	96	90	88	88	66	47	87%
Write 200 words with 90% dialogue Rule Following Utility	100	98	98	92	92	86	76	56	49	41	79%
dialogue-200											87.63%
dialogue-500
Write 500 words with 30% dialogue Rule Following Utility	93	48	38	33	30	26	13	7	5	0	29%
Write 500 words with 50% dialogue Rule Following Utility	98	80	50	50	13	9	1	0	0	0	30%
Write 500 words with 70% dialogue Rule Following Utility	45	39	33	29	10	1	1	0	0	0	16%
dialogue-500											25.04%
Ungrouped
Write unattributed dialogue Rule Following	100	100	100	100	100	100	100	100	100	0	90%
61.15%

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	100	100%
Friend got new kittens (German) Language	100	100	100	100	0	80%
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	100	56	91%
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%
98.22%

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	100	100	100	100	100	100	100	100	100	100%
Write sentences with 10 words each Utility	100	100	100	100	100	100	100	100	100	100	100%
Write sentences with 20 words each Utility	100	100	100	100	100	100	100	100	100	83	98%
99.42%

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	50	50	50	50	50	75%
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	100	100%
pov-count											91.67%
95.83%

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	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	97	96	95	97%
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	99	96	96	92	92	97%
Generic Prompt								99.18%
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	100	100	100	100	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	99	99	99	98	98	98	98	99%
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	100	99	96	99%
Specific Prompt								99.73%
99.46%

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	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%
92.00%

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	100	100	100%
50 sentence summary Utility	100	100	100	100	100	100	100	100	100	100	100%
sentences											100.00%
words
10 word summary Utility	100	100	100	100	100	100	100	0	0	0	70%
20 word summary Utility	100	100	100	100	100	100	100	98	0	0	80%
50 word summary Utility	100	100	100	100	100	100	100	100	100	27	93%
100 word summary Utility	100	100	100	100	100	100	100	100	100	9	91%
200 word summary Utility	100	100	100	100	100	100	2	0	0	0	60%
words											78.72%
91.81%