Claude Fable 5 vs Claude Mythos 5
Claude Fable 5 and Claude Mythos 5 share the same Mythos-class architecture, but they are not interchangeable products. Fable 5 is the generally available Claude route for production teams, while Mythos 5 is invite-only through Project Glasswing for approved cybersecurity defenders and biomedical researchers. Anthropic's launch table reports the higher Fable-or-Mythos score, and starred rows are Mythos 5 only; this page keeps those attributions separate.
Pick Claude Fable 5 for normal production adoption: it has public Claude API, Bedrock, Vertex AI, and Microsoft Foundry routes at $10/M input and $50/M output. Track Claude Mythos 5 only if you are eligible for Project Glasswing and need the lifted cybersecurity or biology safeguards. Do not attribute Mythos 5 starred benchmark scores, including Terminal-Bench 2.1 88.0% and HLE with-tools 64.5%, to Fable 5.
Decision scorecard
Local evidence first| Signal | Claude Fable 5 | Claude Mythos 5 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 1m |
| Cheapest output | $50/1M tokens | $50/1M tokens |
| Provider routes | 4 tracked | 3 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Claude Fable 5 has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Claude Fable 5 for Coding, RAG, and Agents.
- Claude Mythos 5 uniquely exposes Code execution in local model data.
- Local decision data tags Claude Mythos 5 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.
Claude Fable 5
$20,500
Cheapest tracked route/tier: Anthropic
Claude Mythos 5
$20,500
Cheapest tracked route/tier: Anthropic
Estimated monthly gap: $0.00. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Anthropic, AWS Bedrock, and GCP Vertex AI; start route-level A/B tests there.
- Cheapest tracked output pricing is tied, so migration risk shifts to quality, latency, and provider packaging.
- Claude Mythos 5 adds Code execution in local capability data.
- Provider overlap exists on Anthropic, AWS Bedrock, and GCP Vertex AI; start route-level A/B tests there.
- Cheapest tracked output pricing is tied, so migration risk shifts to quality, latency, and provider packaging.
- Check replacement coverage for Code execution before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-06-09 | 2026-06-09 |
| Context window | 1m | 1m |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Claude Fable 5 | Claude Mythos 5 |
|---|---|---|
| Input price | $10/1M tokens | $10/1M tokens |
| Output price | $50/1M tokens | $50/1M tokens |
| Providers |
Capabilities
| Capability | Claude Fable 5 | Claude Mythos 5 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The access model is the practical split. Claude Fable 5 is the broadly available model Anthropic wants most developers to call, with listed pricing and mainstream provider routes. Claude Mythos 5 is source-backed as a distinct model, but access is restricted to approved Project Glasswing participants, with Bedrock and Vertex availability described as limited rather than self-serve.
The benchmark table needs a guardrail before any score comparison. Anthropic's Fable 5/Mythos 5 launch table shows the higher score between the two models. Rows marked with an asterisk are Mythos 5 scores, not Fable 5 scores. LLMReference seeds Fable 5 only with unstarred rows or independent third-party rows, so the Fable 5 page gets SWE-bench Pro 80.3%, Vals.ai SWE-bench Verified 96%, OSWorld-Verified 85.0%, and GDPval-AA ELO 1932.
Mythos 5 exists for restricted-domain work. Its starred Terminal-Bench 2.1 and HLE rows reflect the model with safety classifiers lifted for Glasswing contexts. Fable 5 routes sensitive biology, cybersecurity, and distillation requests through safer behavior, so copying Mythos-only scores onto Fable would overstate what a normal production caller should expect.
Pricing is similar on the first-party numbers but not equivalent in procurement risk. The tracked Anthropic rows list both Fable 5 and Mythos 5 at $10/M input and $50/M output. Fable 5 has normal listed availability; Mythos 5 pricing is partner-listed and access-gated, so eligibility and provider approval matter before token math.
For most teams, the migration path is Opus or Sonnet to Fable 5, not Mythos 5. Use Mythos 5 as a specialized restricted-access benchmark and safety-policy reference. Use Fable 5 for the actual model-provider decision unless your organization has explicit Glasswing approval.
FAQ
Is Claude Mythos 5 available to normal Claude API users?
No. Claude Mythos 5 is tracked as Project Glasswing invite-only access for approved cybersecurity defense and biomedical research organizations. Claude Fable 5 is the generally available Mythos-class model for normal production use.
Can I use Mythos 5 benchmark scores for Claude Fable 5?
Do not copy starred Mythos 5 scores onto Fable 5. Anthropic's shared launch table reports the higher Fable-or-Mythos score, and starred rows are Mythos 5 only. Fable 5 should use only unstarred launch rows or independent Fable-specific measurements.
Which benchmark rows are Fable 5 evidence?
The seeded Fable 5 rows are SWE-bench Pro 80.3%, Vals.ai SWE-bench Verified 96%, OSWorld-Verified 85.0%, and GDPval-AA ELO 1932. Terminal-Bench 2.1 88.0% and HLE with-tools 64.5% are Mythos 5 rows.
Which should I choose for production?
Choose Claude Fable 5 for ordinary production work because it has broadly available provider routes and listed pricing. Consider Claude Mythos 5 only if your organization has Project Glasswing access and your workload specifically needs the restricted-domain safety-policy changes.
Continue comparing
Last reviewed: 2026-06-09. Data sourced from public model cards and provider documentation.