Claude Mythos Preview vs Mistral Medium 3.5
Claude Mythos Preview (2026) and Mistral Medium 3.5 (2026) are frontier-tier reasoning models from Anthropic and MistralAI. Claude Mythos Preview ships a 1M-token context window, while Mistral Medium 3.5 ships a 256K-token context window. On SWE-bench Verified, Claude Mythos Preview leads by 16.3 pts. On pricing, Mistral Medium 3.5 costs $1.5/1M input tokens versus $25/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Mistral Medium 3.5 is ~1567% cheaper at $1.5/1M; pay for Claude Mythos Preview only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Mythos Preview | Mistral Medium 3.5 |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1M | 256K |
| Cheapest output | $125/1M tokens | $7.5/1M tokens |
| Provider routes | 2 tracked | 2 tracked |
| Shared benchmarks | SWE-bench Verified leader | 1 rows |
Decision tradeoffs
- Claude Mythos Preview leads the largest shared benchmark signal on SWE-bench Verified by 16.3 points.
- Claude Mythos Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Mythos Preview uniquely exposes Code execution in local model data.
- Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
- Mistral Medium 3.5 has the lower cheapest tracked output price at $7.5/1M tokens.
- Local decision data tags Mistral Medium 3.5 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
Claude Mythos Preview
$51,250
Cheapest tracked route: Anthropic
Mistral Medium 3.5
$3,075
Cheapest tracked route: Mistral AI Studio
Estimated monthly gap: $48,175. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Claude Mythos Preview and Mistral Medium 3.5; plan for SDK, billing, or endpoint changes.
- Mistral Medium 3.5 is $118/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Code execution before moving production traffic.
- No overlapping tracked provider route is sourced for Mistral Medium 3.5 and Claude Mythos Preview; plan for SDK, billing, or endpoint changes.
- Claude Mythos Preview is $118/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Mythos Preview adds Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-07 | 2026-04-29 |
| Context window | 1M | 256K |
| Parameters | — | 128B |
| Architecture | decoder only | decoder only |
| License | Proprietary | Mistral License |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Pricing attribute | Claude Mythos Preview | Mistral Medium 3.5 |
|---|---|---|
| Input price | $25/1M tokens | $1.5/1M tokens |
| Output price | $125/1M tokens | $7.5/1M tokens |
| Providers |
Capabilities
| Capability | Claude Mythos Preview | Mistral Medium 3.5 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | No |
Benchmarks
| Benchmark | Claude Mythos Preview | Mistral Medium 3.5 |
|---|---|---|
| SWE-bench Verified | 93.9 | 77.6 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Mythos Preview at 93.9 and Mistral Medium 3.5 at 77.6, with Claude Mythos Preview ahead by 16.3 points. The largest visible gap is 16.3 points on SWE-bench Verified, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on code execution: Claude Mythos Preview. Both models share vision, multimodal input, reasoning mode, and function calling, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Mythos Preview lists $25/1M input and $125/1M output tokens, while Mistral Medium 3.5 lists $1.5/1M input and $7.5/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Mistral Medium 3.5 lower by about $51.70 per million blended tokens. Availability is 2 providers versus 2, so concentration risk also matters.
Choose Claude Mythos Preview when coding workflow support and larger context windows are central to the workload. Choose Mistral Medium 3.5 when vision-heavy evaluation and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Mythos Preview or Mistral Medium 3.5?
Claude Mythos Preview supports 1M tokens, while Mistral Medium 3.5 supports 256K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Mythos Preview or Mistral Medium 3.5?
Mistral Medium 3.5 is cheaper on tracked token pricing. Claude Mythos Preview costs $25/1M input and $125/1M output tokens. Mistral Medium 3.5 costs $1.5/1M input and $7.5/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Mythos Preview or Mistral Medium 3.5 open source?
Claude Mythos Preview is listed under Proprietary. Mistral Medium 3.5 is listed under Mistral License. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Mythos Preview or Mistral Medium 3.5?
Both Claude Mythos Preview and Mistral Medium 3.5 expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Claude Mythos Preview or Mistral Medium 3.5?
Both Claude Mythos Preview and Mistral Medium 3.5 expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Claude Mythos Preview and Mistral Medium 3.5?
Claude Mythos Preview is available on Anthropic and Microsoft Foundry. Mistral Medium 3.5 is available on Mistral AI Studio and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-16. Data sourced from public model cards and provider documentation.