claude-mythos-5

Claude Mythos 5 is Anthropic's highest-capability model, designed for the most demanding tasks where quality is the only constraint. It is a reasoning model — meaning it applies extended chain-of-thought processing before producing a final answer — and is designed for the most demanding tasks where quality is the only constraint. Mythos 5 targets frontier research, advanced multi-step agentic workflows, complex scientific analysis, and tasks where every other model in the lineup falls short. It supports a 1M+ token context window, vision inputs, tool use, and streaming.

Claude Mythos 5 is priced at $10.00 per million input tokens and $50.00 per million output tokens. Prompt caching reduces repeated input to $1.00/1M. At 1,000 input + 500 output tokens per call, the cost is approximately $0.035 per 1,000 API calls. As a reasoning model, actual per-query costs are typically higher because the internal thinking process generates additional output tokens before the visible response. For workloads where Mythos 5's top-of-leaderboard quality is genuinely required, the cost premium is justified — but for the majority of production tasks, Claude Opus 5 or Claude Fable 5 deliver comparable results at lower cost.

Claude Mythos 5 supports a 1M+ token context window, enabling analysis of entire codebases, book-length documents, or extended multi-session conversation histories in a single call. As a reasoning model, latency is higher than standard models — median time-to-first-token is approximately 2–5 seconds depending on task complexity, with harder reasoning tasks taking longer. Throughput is approximately 40–50 tokens per second for the visible output portion. The extended reasoning process is not exposed in the API response by default, though Anthropic's extended thinking API surfaces the thinking tokens for inspection and debugging.

Claude Mythos 5 is best suited to tasks at the frontier of model capability: novel scientific reasoning, advanced mathematics, complex multi-agent orchestration, long-horizon planning, and any task where Claude Opus 5 or Fable 5 produce measurably insufficient results. Its reasoning architecture makes it particularly strong on tasks requiring multi-step deduction, hypothesis generation, and self-correction — capabilities that standard (non-reasoning) models struggle with. For production inference serving, customer-facing chat, or high-volume pipelines, the latency and cost profile make it unsuitable; use Claude Sonnet 5 or Haiku 4.5 for those workloads.

Claude Mythos 5 sits at the apex of Anthropic's model lineup, above Claude Opus 5 and Claude Fable 5. Its closest competitors are frontier-tier reasoning models from OpenAI and other providers. Mythos 5 leads on overall benchmark score but carries the highest price in the Claude lineup. For teams where the marginal quality improvement over Claude Opus 5 is measurable on their specific task, Mythos 5 is the right choice. For most production workloads, Claude Fable 5 or Claude Opus 5 deliver frontier-class quality at lower cost.