{"slug": "head-to-head-grok-4-3-vs-mistral-medium-3-5", "title": "Head to head: grok-4.3 vs mistral-medium-3-5", "summary": "In a head-to-head benchmark of four text-generation tasks, xAI's Grok-4.3 scored 34.0 to Mistral Medium 3-5's 31.0, winning on structured output and instruction-following. Grok-4.3 outperformed on vendor-delay-email and messy-orders-to-json, while Mistral Medium 3-5 won on python-log-redactor and meeting-summary-actions. The results position Grok-4.3 as more reliable for tasks where output format and business brief compliance are critical.", "body_md": "The score says **34.0 to 31.0 for grok-4.3**, and that result tracks the most important misses. grok-4.3 took **vendor-delay-email** and **messy-orders-to-json**, while mistral-medium-3-5 won **python-log-redactor** and **meeting-summary-actions**. That is an even split on paper, but not an even split in impact: grok-4.3 was better where brittle instruction-following would actually break the deliverable.\n\nThe clearest example is **messy-orders-to-json**. grok-4.3 did the simple but essential thing: output **valid JSON only**, parsed the valid rows, and skipped the line missing `order_id`\n\n. mistral-medium-3-5 wrapped otherwise correct content in Markdown code fences, which is exactly the kind of avoidable formatting error that turns a usable answer into a failed one. In structured-output work, that matters more than polish.\n\ngrok-4.3 also had the stronger showing on **vendor-delay-email**. It hit the brief with a proper subject line, the right accountable tone, correct treatment of the delayed portion of the order, and stayed within the **140–180 word** target. mistral-medium-3-5 wrote a decent note, but it came in short and inserted an unsupported year for **May 28**. That is not a stylistic quibble; it is a factual and instruction-level miss in a routine workplace task.\n\nmistral-medium-3-5 absolutely earned its wins. On **python-log-redactor**, it was closer to spec because it preserved trailing punctuation for `token`\n\nand `api_key`\n\nvalues, whereas grok-4.3 dropped punctuation and used a narrower secret pattern. On **meeting-summary-actions**, both models were accurate, but mistral-medium-3-5 better matched the requested structure with **exactly three concise summary bullets** and cleaner separation of extracted details. Those are real advantages, especially for users who care about formatting precision.\n\nStill, the verdict is straightforward: **grok-4.3 is the better model here**. mistral-medium-3-5 was sharper on a redaction edge case and cleaner on summary formatting, but grok-4.3 was more reliable on the tasks where following the output contract and the business brief was non-negotiable.\n\n### How they were tested\n\nWe ran 4 fresh text tasks, generated on the fly for this matchup so neither model could prepare in advance, and had gpt-5.4 score each one. grok-4.3 scored 34.0 to mistral-medium-3-5's 31.0.\n\n#### 1. python-log-redactor\n\nLanguage: Python 3.11. Write a function `redact_log(line: str) -> str`\n\nthat masks sensitive values in application log lines before they are stored. Rules: - Replace any IPv4 address with `[IP]`\n\n. - Replace any email address with `[EMAIL]`\n\n. - Replace any value of `token=...`\n\nor `api_key=...`\n\nwith `token=[SECRET]`\n\n/ `api_key=[SECRET]`\n\nand preserve trailing punctuation. - Do not change timestamps, paths, or non-sensitive numbers. Examples: `2026-02-03T07:11:04Z login ok user=mina@farside.tools ip=198.51.100.24 token=abC123-XY9`\n\n-> `2026-02-03T07:11:04Z login ok user=[EMAIL] ip=[IP] token=[SECRET]`\n\n`warn api_key=z9_z9_z9, path=/v1/export client_ip=203.0.113.7`\n\n-> `warn api_key=[SECRET], path=/v1/export client_ip=[IP]`\n\nReturn code only.\n\n**Winner: mistral-medium-3-5** — B better follows the requirement to preserve trailing punctuation for token/api_key values, while A drops punctuation and only matches a narrower secret character set. Both use a permissive IPv4 regex and are otherwise reasonable, but B is closer to the spec overall.\n\n#### 2. vendor-delay-email\n\nDraft an email to a procurement manager at Northline Biologics. Context: our company, Alder Peak Instruments, will deliver 420 cryogenic vial racks 9 days late because a powder-coating batch failed inspection. We can ship 180 racks on the original date, the remaining 240 on May 28. Offer either a 6% discount on the delayed portion or free expedited freight. Tone: accountable, calm, professional. Length: 140–180 words. Include a clear subject line.\n\n**Winner: grok-4.3** — A better satisfies the brief with a clear subject line, accountable and professional tone, correct handling of the delayed portion, and a length that fits the 140–180 word requirement. B is concise and polished, but it appears under the requested length and introduces an unsupported year for May 28.\n\n#### 3. meeting-summary-actions\n\nSummarize the meeting notes below in 3 bullet points, then extract: (a) decision, (b) owner for each action item, (c) next meeting date. Notes: - 9:00 standup for the Bristlecone mobile app. - Nia said Android crash rate rose after v4.8.1; mostly on Samsung A52 when users open saved route maps offline. - Pavel found the issue likely tied to the new tile cache. Hotfix candidate ready by Thursday afternoon. - Irene from support said 19 tickets mention blank maps; 7 of those are from paid field teams. - Team agreed not to roll back 4.8.1 because the battery drain fix is too important. - Action: Pavel to ship hotfix build to QA by Thu 3 PM. - Action: Nia to post an in-app status notice draft by noon today. - Action: Irene to tag all related support tickets with `offline-map-blank`\n\n. - Next sync: Friday, April 17 at 10:30 AM.\n\n**Winner: mistral-medium-3-5** — Both are accurate, but B adheres more closely to the requested format with exactly 3 concise summary bullets and clearly separated extracted details. A is also correct, but its third bullet is vague and less informative than B’s summary.\n\n#### 4. messy-orders-to-json\n\nConvert the messy order lines below into valid JSON only. Output schema: { \"orders\": [ {\"order_id\": string, \"customer\": string, \"sku\": string, \"qty\": integer, \"unit_price\": number, \"rush\": boolean} ] } Rules: - One object per valid line. - Trim spaces. - `qty`\n\nis an integer. - `unit_price`\n\nis a number without currency symbols. - `rush`\n\nis true only for yes/y. - Skip the line with a missing order_id. Data: ORD-771 | customer: Leeward Studio | sku=PX-14 | qty 3 | unit $19.50 | rush yes ORD-772|customer:Mariner Vale|sku=Q-9|qty 12|unit $4|rush no | customer: Hollow Ember | sku=LM-2 | qty 5 | unit $11.00 | rush yes ORD-774 | customer: Ilex Foods | sku=AA-88 | qty 1 | unit $250.00 | rush y\n\n**Winner: grok-4.3** — Model A follows the instruction to output valid JSON only and correctly parses all valid lines while skipping the missing order_id. Model B's content is otherwise correct, but the surrounding Markdown code fences violate the 'JSON only' requirement.\n\nSee every prompt and the full side-by-side outputs in the [interactive Head-to-Head](/head-to-head/head-to-head-grok-4-3-vs-mistral-medium-3-5).", "url": "https://wpnews.pro/news/head-to-head-grok-4-3-vs-mistral-medium-3-5", "canonical_source": "https://runtimewire.com/article/head-to-head-grok-4-3-vs-mistral-medium-3-5", "published_at": "2026-07-08 14:07:07+00:00", "updated_at": "2026-07-08 15:00:04.366888+00:00", "lang": "en", "topics": ["large-language-models", "ai-products", "ai-tools"], "entities": ["xAI", "Mistral AI", "Grok-4.3", "Mistral Medium 3-5", "GPT-5.4", "Alder Peak Instruments", "Northline Biologics"], "alternates": {"html": "https://wpnews.pro/news/head-to-head-grok-4-3-vs-mistral-medium-3-5", "markdown": "https://wpnews.pro/news/head-to-head-grok-4-3-vs-mistral-medium-3-5.md", "text": "https://wpnews.pro/news/head-to-head-grok-4-3-vs-mistral-medium-3-5.txt", "jsonld": "https://wpnews.pro/news/head-to-head-grok-4-3-vs-mistral-medium-3-5.jsonld"}}