Claude Mythos 5 vs GPT-5.5-Cyber
Claude Mythos 5 (2026) and GPT-5.5-Cyber (2026) are frontier-tier reasoning models from Anthropic and OpenAI. Claude Mythos 5 ships a 1m-token context window, while GPT-5.5-Cyber ships a not-yet-sourced context window. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads. It focuses on practical selection signals rather than broad model-family marketing.
Claude Mythos 5 is safer overall; choose GPT-5.5-Cyber when vision-heavy evaluation matters.
Decision scorecard
Local evidence first| Signal | Claude Mythos 5 | GPT-5.5-Cyber |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps and multimodal apps |
| Decision fit | Coding, RAG, and Agents | Vision |
| Context window | 1m | — |
| Cheapest output | $50/1M tokens | - |
| Provider routes | 3 tracked | 0 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Claude Mythos 5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Mythos 5 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Mythos 5 uniquely exposes Function calling, Tool use, and Structured outputs in local model data.
- Local decision data tags Claude Mythos 5 for Coding, RAG, and Agents.
- Local decision data tags GPT-5.5-Cyber for Vision.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Mythos 5
$20,500
Cheapest tracked route/tier: Anthropic
GPT-5.5-Cyber
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Claude Mythos 5 and GPT-5.5-Cyber; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Function calling, Tool use, and Structured outputs before moving production traffic.
- No overlapping tracked provider route is sourced for GPT-5.5-Cyber and Claude Mythos 5; plan for SDK, billing, or endpoint changes.
- Claude Mythos 5 adds Function calling, Tool use, and Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-06-09 | 2026-04-30 |
| Context window | 1m | — |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | 2025-12 |
Pricing and availability
| Pricing attribute | Claude Mythos 5 | GPT-5.5-Cyber |
|---|---|---|
| Input price | $10/1M tokens | - |
| Output price | $50/1M tokens | - |
| Providers | - |
Capabilities
| Capability | Claude Mythos 5 | GPT-5.5-Cyber |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Deep dive
The capability footprint differs most on function calling: Claude Mythos 5, tool use: Claude Mythos 5, structured outputs: Claude Mythos 5, and code execution: Claude Mythos 5. Both models share vision, multimodal input, and reasoning mode, 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.
Pricing coverage is uneven: Claude Mythos 5 has $10/1M input tokens and GPT-5.5-Cyber has no token price sourced yet. Provider availability is 3 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Claude Mythos 5 when coding workflow support and broader provider choice are central to the workload. Choose GPT-5.5-Cyber when vision-heavy evaluation are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Is Claude Mythos 5 or GPT-5.5-Cyber open source?
Claude Mythos 5 is listed under Proprietary. GPT-5.5-Cyber is listed under Proprietary. 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 5 or GPT-5.5-Cyber?
Both Claude Mythos 5 and GPT-5.5-Cyber expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Claude Mythos 5 or GPT-5.5-Cyber?
Both Claude Mythos 5 and GPT-5.5-Cyber expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for reasoning mode, Claude Mythos 5 or GPT-5.5-Cyber?
Both Claude Mythos 5 and GPT-5.5-Cyber expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for function calling, Claude Mythos 5 or GPT-5.5-Cyber?
Claude Mythos 5 has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Mythos 5 and GPT-5.5-Cyber?
Claude Mythos 5 is available on Anthropic, AWS Bedrock, and GCP Vertex AI. GPT-5.5-Cyber is available on the tracked providers still being sourced. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-15. Data sourced from public model cards and provider documentation.