Mistral Medium 3.5 (Reasoning)

mistralai/mistral-medium-3-5

Mistral Medium 3.5 (Reasoning)

via OpenRouter

Release Date

Apr 30th, 2026

Context Size

262k

Reasoning

Yes

Benchmark Cost

$5.73

Speed

101.8 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	81	79	76	75	72	77%
Horror: alone in an eerie place at night Creative Writing Hallucination	83	81	80	79	77	80%
Literary fiction: old friends reunite Creative Writing Hallucination	90	89	88	84	81	86%
Mystery: examining a crime scene Creative Writing Hallucination	83	82	82	78	78	81%
Romance: separated couple reunites Creative Writing Hallucination	90	87	83	81	80	84%
Thriller: chase through city streets Creative Writing Hallucination	87	84	82	80	74	82%
Detailed Writing Rules						81.49%
genre
Fantasy: entering an ancient ruin Creative Writing Hallucination	80	78	77	74	72	76%
Horror: alone in an eerie place at night Creative Writing Hallucination	90	86	84	80	80	84%
Literary fiction: old friends reunite Creative Writing Hallucination	85	81	80	80	79	81%
Mystery: examining a crime scene Creative Writing Hallucination	85	79	79	78	75	79%
Romance: separated couple reunites Creative Writing Hallucination	87	86	81	78	77	82%
Thriller: chase through city streets Creative Writing Hallucination	84	83	82	81	80	82%
genre						80.69%
Novelcrafter Default Prompt
Fantasy: entering an ancient ruin Creative Writing Hallucination	80	79	78	76	70	76%
Horror: alone in an eerie place at night Creative Writing Hallucination	83	81	80	77	75	79%
Literary fiction: old friends reunite Creative Writing Hallucination	89	84	84	84	80	84%
Mystery: examining a crime scene Creative Writing Hallucination	85	84	83	81	81	83%
Romance: separated couple reunites Creative Writing Hallucination	88	87	86	86	82	86%
Thriller: chase through city streets Creative Writing Hallucination	86	83	82	82	82	83%
Novelcrafter Default Prompt						81.84%
81.34%

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	96	96	96	96	96	96%
Medium: The Hollow (Inferred) Tooling Reasoning	96	96	96	96	96	96%
Medium: Through the Thornveil (Scattered) Tooling Reasoning	97	97	97	97	97	97%
Short: The Rusty Lantern (Explicit) Tooling Reasoning	96	96	96	96	95	96%
96.29%

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	50	35	32	31	30	28	27	27	27	2	29%
Long text (~1594 words), small codex (11 entries) Hallucination	42	38	35	35	33	32	31	31	17	17	31%
Short text (~524 words), big codex (51 entries) Hallucination	50	50	50	50	42	42	30	17	17	13	36%
Short text (~524 words), small codex (11 entries) Hallucination	50	42	38	35	17	17	17	17	17	13	26%
basic entries											30.46%
detailed entries
Long text (~1594 words), big codex (51 detailed entries) Hallucination	50	50	50	50	50	50	50	50	50	50	50%
Long text (~1594 words), small codex (11 detailed entries) Hallucination	38	35	35	33	31	31	17	13	10	10	25%
Short text (~524 words), big codex (51 detailed entries) Hallucination	50	50	50	50	50	50	50	50	50	42	49%
Short text (~524 words), small codex (11 detailed entries) Hallucination	50	50	50	50	50	50	50	50	17	17	43%
detailed entries											41.92%
36.19%

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	83	79	75	72	72	71	69	69	68	67	72%
Large codex (40 entries), short passage (165 words) Tooling Reasoning	96	94	94	94	92	92	92	92	92	90	93%
Small codex (7 entries), long passage (734 words) Tooling Reasoning	88	83	83	83	83	83	83	79	79	79	83%
Small codex (7 entries), short passage (165 words) Tooling Reasoning	100	100	100	100	100	100	100	100	100	100	100%
matrix											86.94%
tiers
5 codex entries Tooling Reasoning	83	83	83	83	76	76	76	76	76	76	79%
10 codex entries Tooling Reasoning	100	100	100	100	100	100	100	100	100	100	100%
20 codex entries Tooling Reasoning	96	96	96	96	96	96	96	92	92	92	95%
40 codex entries Tooling Reasoning	95	92	92	92	88	87	87	83	83	83	88%
tiers											90.42%
88.68%

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	50	50	50	50	50	50	50	50	50	50	50%
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%
90.91%

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	50	38	22	2	2	0	0	0	0	0	11%
Write 200 words with 50% dialogue Rule Following Utility	79	32	0	0	0	0	0	0	0	0	11%
Write 200 words with 90% dialogue Rule Following Utility	56	19	18	18	18	18	18	18	18	18	22%
dialogue-200											14.90%
dialogue-500
Write 500 words with 30% dialogue Rule Following Utility	45	45	36	0	0	0	0	0	0	0	13%
Write 500 words with 50% dialogue Rule Following Utility	50	28	15	6	0	0	0	0	0	0	10%
Write 500 words with 70% dialogue Rule Following Utility	48	44	40	37	10	6	4	3	2	0	19%
dialogue-500											13.96%
Ungrouped
Write unattributed dialogue Rule Following	100	100	100	100	100	100	100	100	100	100	100%
26.65%

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	100	100%
Friend got new kittens (Tagalog) Language	100	100	100	100	100	100%
100.00%

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	80	96%
Character dialogue (German) in a story Language	100	100	100	91	83	95%
Character dialogue (Hindi) in a story Language	50	46	45	44	44	46%
Character dialogue (Italian) in a story Language	100	100	100	100	100	100%
Character dialogue (Spanish) in a story Language	100	100	100	100	88	98%
86.89%

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	95	92	92	90	90	86	84	84	77	59	85%
Write sentences with 20 words each Utility	59	51	42	35	30	20	15	7	0	0	26%
70.30%

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	0	0	0	0	0	0	0	0	0	0	0%
outline-count											66.67%
pov-count
Count point of views for Jack and Olivia Utility	100	100	50	50	50	50	50	50	50	0	55%
Count point of views for Jack Harper Utility	0	0	0	0	0	0	0	0	0	0	0%
Count point of views for Olivia Utility	100	0	0	0	0	0	0	0	0	0	10%
pov-count											21.67%
44.17%

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	78	76	73	70	69	73%
Family relationship tree Tooling Reasoning Hallucination	81	81	80	80	80	81%
76.84%

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	98	98	98	98	98	98	97	98%
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	93	93	92	91	91	91	90	92%
POV shift: 3rd person to 1st person (Elena's perspective) Text Editing	99	99	99	99	99	99	99	99%
Tense rewriting: past to present Text Editing	89	89	88	88	88	88	88	88%
Generic Prompt								97.36%
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	100	100	100	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	96	96	99%
Passive voice → active voice Text Editing Hallucination	93	93	93	92	92	92	91	92%
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	100	100	100%
Specific Prompt								99.00%
98.18%

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	100	100%
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%
100.00%

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	98	100%
20 sentence summary Utility	100	100	100	100	100	100	100	98	98	9	91%
50 sentence summary Utility	77	0	0	0	0	0	0	0	0	0	8%
sentences											79.63%
words
10 word summary Utility	100	100	100	100	100	92	92	92	92	92	96%
20 word summary Utility	77	77	77	77	77	77	77	54	54	27	68%
50 word summary Utility	98	92	92	92	9	0	0	0	0	0	38%
100 word summary Utility	100	98	98	77	54	27	2	2	2	0	46%
200 word summary Utility	0	0	0	0	0	0	0	0	0	0	0%
words											49.64%
72.79%