Claude Fable 5 vs Mistral Medium 3.5
Anthropic Claude Fable 5 | Mistral Mistral Medium 3.5 | |
|---|---|---|
| Overview | ||
| Company | Anthropic | Mistral |
| Release date | Jun 9 2026 | Apr 29 2026 |
| Access | Proprietary | Open Weight |
| Specifications | ||
Parameters | — | 128B |
Context window | 1M | 256k |
| Benchmarks | ||
Nonsense detection BullshitBench v2Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 56% | — |
Agentic coding SWE-Bench ProCan the AI fix real bugs in real software? It's handed actual problems from open-source projects and has to write code that genuinely solves them. Higher is better. | 80.3% | — |
Coding SWE-Bench VerifiedReal coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 95.5%Best | 77.6% |
Agentic coding CursorBench v3.1Cursor's own test of harder, real-world coding tasks inside a code editor. Higher is better. | 72.9% | — |
Agentic coding DeepSWE 1.0Artificial Analysis' independent test of deep, agentic software-engineering work — the AI has to plan and carry out substantial coding tasks end to end. Higher is better. | 66.1% | — |
Next.js coding Next.js EvalsVercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better. | 92% | — |
Agentic terminal coding Terminal-Bench 2.1Can the AI work in a command-line terminal — running commands and finishing technical setup tasks the way a developer would? Higher is better. | 88% | — |
Agentic computer use OSWorld-VerifiedCan the AI actually operate a computer — clicking, typing, and using real apps — to finish tasks on its own? Higher is better. | 85% | — |
Agentic legal work Harvey's Legal Agent BenchmarkHarvey's test of whether an AI agent can complete real legal work — drafting and reviewing documents, working with spreadsheets and presentations, and navigating files the way a lawyer's assistant would. Higher is better. | 11.25% | — |
Tax questions TaxEval v2A set of real tax questions created by Vals AI — can the AI give accurate answers about tax rules and filings? Higher is better. | 76.94% | — |
Medical admin work MedScribeCan the AI support doctors with their administrative work, like notes and paperwork? Created by Vals AI. Higher is better. | 88.52% | — |
Knowledge work GDPval-AAMeasures how well the AI does economically valuable knowledge work, judged against human experts. Shown as a rating (like a chess Elo) — higher is better. | 1932 | — |
| Timeline | ||
| Release gap | Mistral Medium 3.5 shipped 41 days before Claude Fable 5 | |
Which is better: Claude Fable 5 or Mistral Medium 3.5?
Claude Fable 5 leads Mistral Medium 3.5 on 1 of the 1 benchmark they both report (SWE-Bench Verified). Mistral Medium 3.5 shipped 41 days before Claude Fable 5, so benchmark comparisons should account for the intervening progress.
Context windows are 1M (Claude Fable 5) vs 256k (Mistral Medium 3.5). Claude Fable 5 is proprietary, while Mistral Medium 3.5 is open weight.
On SWE-Bench Verified, Claude Fable 5 leads at 95.5% vs Mistral Medium 3.5 at 77.6%.
Frequently asked questions
Claude Fable 5 was released by Anthropic on Jun 9 2026.
Mistral Medium 3.5 was released by Mistral on Apr 29 2026.
Claude Fable 5 leads on SWE-Bench Verified — Claude Fable 5 95.5% vs Mistral Medium 3.5 77.6%.
Claude Fable 5 has a 1M context window; Mistral Medium 3.5 has 256k.
Claude Fable 5 is a proprietary model released by Anthropic. Mistral Medium 3.5 is an open weight model released by Mistral.