Claude Mythos Preview vs Qwen3.5-397B-A17B

Claude Mythos Preview (2026) and Qwen3.5-397B-A17B (2026) are frontier-tier reasoning models from Anthropic and Alibaba. Claude Mythos Preview ships a 1m-token context window, while Qwen3.5-397B-A17B ships a 262k-token context window. On SWE-bench Verified, Claude Mythos Preview leads by 17.7 pts. On pricing, Qwen3.5-397B-A17B costs $0.39/1M input tokens versus $25/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

Qwen3.5-397B-A17B is ~6310% cheaper at $0.39/1M; pay for Claude Mythos Preview only for coding workflow support.

Decision scorecard

Local evidence first
SignalClaude Mythos PreviewQwen3.5-397B-A17B
Best forreasoning-heavy apps, multimodal apps, and tool-calling agentsreasoning-heavy apps, multimodal apps, and tool-calling agents
Decision fitCoding, RAG, and AgentsCoding, RAG, and Agents
Context window1m262k
Cheapest output$125/1M tokens$2.34/1M tokens
Provider routes2 tracked4 tracked
Shared benchmarksSWE-bench Verified leader3 shared

Decision tradeoffs

Choose Claude Mythos Preview when...
  • Claude Mythos Preview holds a shared-benchmark lead on SWE-bench Verified, ahead by 17.7 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.
Choose Qwen3.5-397B-A17B when...
  • Qwen3.5-397B-A17B has the lower cheapest tracked output price at $2.34/1M tokens.
  • Qwen3.5-397B-A17B has broader tracked provider coverage for fallback and route flexibility.
  • Local decision data tags Qwen3.5-397B-A17B for Coding, RAG, and Agents.

Monthly cost at traffic

Estimate token spend from the cheapest tracked input and output route or tier on this page.

Lower estimate Qwen3.5-397B-A17B

Claude Mythos Preview

$51,250

Cheapest tracked route/tier: Anthropic

Qwen3.5-397B-A17B

$897

Cheapest tracked route/tier: OpenRouter

Estimated monthly gap: $50,353. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Claude Mythos Preview -> Qwen3.5-397B-A17B
  • No overlapping tracked provider route is sourced for Claude Mythos Preview and Qwen3.5-397B-A17B; plan for SDK, billing, or endpoint changes.
  • Qwen3.5-397B-A17B is $123/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
  • Check replacement coverage for Code execution before moving production traffic.
Qwen3.5-397B-A17B -> Claude Mythos Preview
  • No overlapping tracked provider route is sourced for Qwen3.5-397B-A17B and Claude Mythos Preview; plan for SDK, billing, or endpoint changes.
  • Claude Mythos Preview is $123/1M 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
Released2026-05-012026-02-16
Context window1m262k
Parameters—397B
ArchitectureDecoder OnlyMixture of Experts
LicenseProprietaryApache 2.0OSI-approved
OpennessProprietaryOpen source
WeightsNot releasedAvailable
CodeUnknownUnknown
Commercial useCommercial use: conditionalCommercial use: permitted
Knowledge cutoff2025-12-

Pricing and availability

Pricing attributeClaude Mythos PreviewQwen3.5-397B-A17B
Input price$25/1M tokens$0.39/1M tokens
Output price$125/1M tokens$2.34/1M tokens
Providers
AnthropicMicrosoft Foundry
OpenRouterTogether AIAlibaba Cloud PAI-EASNovita AI

Capabilities

CapabilityClaude Mythos PreviewQwen3.5-397B-A17B
VisionYesYes
MultimodalYesYes
ReasoningYesYes
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesNo
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

BenchmarkClaude Mythos PreviewQwen3.5-397B-A17B
SWE-bench Verified93.976.2
Google-Proof Q&A94.689.3
τ-bench89.286.7

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Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.