Claude Mythos 5
by Anthropic · United StatesClaude Fable 5's capabilities without its safety classifiers, released alongside it for defensive cybersecurity work under Project Glasswing. Same specifications and pricing as Fable 5; access is approved case by case.
Specification
The numbers
- Maker
- Anthropic
- Released
- 2026-06
- Parameters
- Not reported
- Architecture
- Not reported
- Context window
- 1,000,000 tokens
- Max output
- 128,000 tokens
- Input
- Text, Image
- Output
- Text
- Reasoning
- Yes
- Tool calling
- Yes
- Knowledge cutoff
- 2026-01
- Licence
- Proprietary
- Availability
- Invitation only — Project Glasswing
- Weights
- Not released
API model ID: claude-mythos-5
Cost
Price per million tokens
- Input
- $10.00 / M tokens
- Output
- $50.00 / M tokens
- Cached input
- $1.00
- Blended 3:1
- $20.00
Standard first-party API rate, excluding batch discounts. Reasoning models bill thinking tokens as output, so cost per answer can far exceed the cost per token suggests.
Published scores
Benchmarks
Figures published by Anthropic or taken from a public leaderboard. Row last checked 2026-09.
Every reported test
Where these numbers come from
Every score on this page is a published figure, taken from the model's own card, system card, technical report or release post, or from a public leaderboard. CorX Labs did not run these evaluations. Most are self-reported by the lab that built the model, which means they were produced under that lab's own choice of prompt, scaffold and number of attempts — so treat them as a starting point for a shortlist, not as a settled ranking.
A score someone other than the model's maker measured is marked Independent and names its measurer. Those are the stronger numbers on this page — an outside harness has no reason to flatter anyone — and there are not many of them.
Where a figure has not been published, the cell reads Not reported rather than an estimate. Nothing here is inferred, interpolated or guessed. Each model records the month its row was last checked. Full method and caveats.
Head to head
Claude Mythos 5 compared
Same maker
Other models from Anthropic
| Claude Fable 5.1Anthropic | Anthropic | 1M | $10.00 | $50.00 | — | — | — | — | Proprietary |
| Claude Mythos 5.1Anthropic | Anthropic | 1M | $10.00 | $50.00 | — | — | — | — | Proprietary |
| Claude Opus 5Anthropic | Anthropic | 1M | $5.00 | $25.00 | — | — | — | — | Proprietary |
| Claude Sonnet 5Anthropic | Anthropic | 1M | $2.00 | $10.00 | — | — | — | — | Proprietary |
| Claude Fable 5Anthropic | Anthropic | 1M | $10.00 | $50.00 | — | — | — | — | Proprietary |
| Claude Opus 4.5Anthropic | Anthropic | 200K | $5.00 | $25.00 | — | 87% | 96% | 80.9% | Proprietary |
| Claude Haiku 4.5Anthropic | Anthropic | 200K | $1.00 | $5.00 | — | 73% | 77% | 73.3% | Proprietary |
| Claude Sonnet 4.5Anthropic | Anthropic | 1M | $3.00 | $15.00 | — | 83.4% | 87% | 77.2% | Proprietary |
| Claude Opus 4.1Anthropic | Anthropic | 200K | $15.00 | $75.00 | — | 80.9% | 78% | 74.5% | Proprietary |
| Claude Sonnet 4Anthropic | Anthropic | 200K | $3.00 | $15.00 | — | 75.4% | 70.5% | 72.7% | Proprietary |
| Claude 3.7 SonnetAnthropic | Anthropic | 200K | $3.00 | $15.00 | — | 68% | 61.3% | 62.3% | Proprietary |
| Claude 3.5 HaikuAnthropic | Anthropic | 200K | $0.80 | $4.00 | 65% | 41.6% | — | 40.6% | Proprietary |
| Claude 3.5 SonnetAnthropic | Anthropic | 200K | $3.00 | $15.00 | 78% | 65% | — | 49% | Proprietary |
| Claude 3 OpusAnthropic | Anthropic | 200K | $15.00 | $75.00 | 68.5% | 50.4% | — | — | Proprietary |