Anthropic Unveils Claude Mythos Preview: The Capybara Tier Breakthrough

In the realm of pure reasoning, Mythos Preview shows exceptional aptitude for mathematical and logical challenges. It secured a 97.6% score on the USAMO 2026 competition, a metric that validates its ability to handle complex, abstract logic. Additionally, on the GPQA Diamond benchmark, which tests graduate-level knowledge, it achieved 94.5%. These numbers indicate that the model is not just a coding assistant but a genuine research-grade reasoning engine.

• SWE-bench Verified: 93.9%
• SWE-bench Pro: 77.8%
• USAMO 2026: 97.6%
• GPQA Diamond: 94.5%

API Pricing

Due to the limited preview status of Claude Mythos Preview, public API pricing is not currently available. Anthropic has opted for a private, negotiated enterprise model where costs are tailored to the specific security and compliance requirements of the partner organizations. This approach ensures that the high compute costs associated with the 1M context window and Capybara tier are managed sustainably while protecting the model's proprietary nature.

Developers should expect input and output costs to be significantly higher than standard Opus or Sonnet tiers given the computational density required for the Capybara architecture. While exact figures remain confidential, the value proposition lies in the reduced iteration time for complex tasks. Organizations using this model for automated security auditing or large-scale codebase analysis will likely find the cost justified by the reduction in human review hours.

• Pricing Model: Enterprise Negotiated
• Public Tier: N/A
• Estimated Cost: High (Due to Capybara Tier)

Comparison Table

When comparing Claude Mythos Preview against current market leaders, the performance gap in specialized reasoning tasks becomes evident. While generalist models like GPT-5 focus on broad utility, Mythos prioritizes depth and accuracy in specific domains. The comparison below highlights the context and pricing differences that developers must consider when selecting a model for production environments.

• Competitive Advantage: Specialized Reasoning
• Context: 1M vs 128K-256K
• Focus: Security and Code

Use Cases

The primary use case for Claude Mythos Preview is in automated cybersecurity and vulnerability management. Through Project Glasswing, the model can scan codebases for vulnerabilities, generate patches, and even simulate attacks to test defenses. This capability is transformative for DevSecOps pipelines, allowing security teams to shift left and catch critical flaws before deployment.

Beyond security, the model excels in complex reasoning applications such as legal document analysis and scientific research. Its ability to maintain context over 1M tokens makes it ideal for summarizing lengthy regulatory frameworks or analyzing multi-modal datasets in biotech. Developers should leverage this model for tasks requiring high-precision logic rather than simple chat interactions.

• Automated Security Auditing
• Large-Scale Codebase Refactoring
• Legal and Scientific Reasoning
• RAG for Massive Document Sets

Getting Started

Accessing Claude Mythos Preview requires an invitation from Anthropic or a partnership agreement with one of the approved organizations. There is no public SDK or open API endpoint available at this time. Developers interested in this technology should monitor the Anthropic Developer Portal for updates on the partner program application process, which focuses on security clearance and enterprise use cases.

For those who cannot secure a preview slot, the recommended alternative is to use the latest Opus model with the extended context window. While it lacks the Capybara tier reasoning, it remains the most powerful publicly available Anthropic model. Keeping an eye on the official blog is crucial, as the limited preview may expand to a broader beta within the next quarter.

• Access: Partner Invitation Only
• Platform: Anthropic Private Cloud
• Alternative: Opus 4.6 (Public)

Comparison

Model: Claude Mythos Preview | Context: 1,000,000 | Max Output: 512,000 | Input $/M: N/A | Output $/M: N/A | Strength: Reasoning & Security

Model: Claude Opus | Context: 200,000 | Max Output: 100,000 | Input $/M: $15.00 | Output $/M: $75.00 | Strength: General Purpose

Model: GPT-5 | Context: 256,000 | Max Output: 100,000 | Input $/M: $10.00 | Output $/M: $30.00 | Strength: Multimodal

API Pricing — Context: 1,000,000

Sources