Claude Mythos Preview

Overview

Freshness note: Model capabilities, limits, pricing, and availability can change quickly. This profile is a point-in-time snapshot last verified on April 8, 2026.

Claude Mythos Preview is Anthropic’s new gated research-preview model announced on April 7, 2026. Anthropic describes it as a general-purpose frontier model and, more specifically, as its most capable model yet for coding and agentic tasks. The launch matters because Anthropic is not presenting Mythos as just another public Claude plan option. It is introducing the model together with Project Glasswing, an early-access initiative focused on securing critical software with frontier AI.

That distinction is important. Project Glasswing is not a separate model or a replacement product surface. It is the deployment and evaluation initiative built around Mythos Preview, giving selected partners and additional critical-software organizations access for defensive work. Anthropic also says it does not currently plan to make Mythos Preview generally available, which makes this page a snapshot of an unusually restricted but strategically important frontier release.

Capabilities

Anthropic’s public framing is unusually direct: Mythos Preview is a general-purpose model whose most striking current strength is cybersecurity. The official Glasswing materials say the model has already found thousands of high-severity vulnerabilities across critical infrastructure, while the RED-team writeup shows it identifying and exploiting difficult bugs in browsers, operating systems, and major open-source targets.

Anthropic also emphasizes that these cyber capabilities are downstream effects of broader improvements in code, reasoning, and autonomy. That is why the model is relevant beyond security specialists. The same characteristics that make it unusually capable at vulnerability discovery also make it important for autonomous coding, long-running agent loops, and hard software-engineering tasks over large codebases.

Microsoft Foundry’s Anthropic documentation is the clearest official partner source for its broader shape. It describes Mythos Preview as built for defensive security, autonomous coding, and long-running agents, and says the model supports adaptive thinking. In other words, Anthropic is positioning Mythos as a frontier coding-and-agency step change whose current release path happens to be security-first.

Technical Details

The current official partner documentation lists these practical anchors:

• 1M token context window
• 128K max output
• text and image input with text output
• adaptive thinking support

Anthropic’s own public announcement materials focus more on demonstrated behavior than on a polished standalone spec sheet. The RED-team writeup says Mythos Preview performs strongly across the board, but is especially capable at computer-security tasks. It also says many of the observed exploit-development abilities were not explicitly trained as a separate objective, but emerged from broader gains in code understanding, reasoning, and autonomy.

Operationally, the important detail is not just “bigger Claude.” It is that Anthropic is treating Mythos as a model that can sustain coherent work over long horizons, act more autonomously on difficult coding problems, and cross a threshold where safety controls and access restrictions become central deployment concerns.

Pricing & Access

Anthropic’s current official position is deliberately narrow:

• gated research preview only
• access prioritized for defensive cybersecurity use cases
• available to Project Glasswing participants and additional selected critical-software organizations
• accessible through the Claude API, Amazon Bedrock, Google Cloud Vertex AI, and Microsoft Foundry

Anthropic’s project page lists pricing for participants at:

• Input: $25 per 1M tokens
• Output: $125 per 1M tokens

Anthropic also says it has committed up to $100M in usage credits for Project Glasswing and related participants during the research preview. At the same time, the company explicitly says it does not plan to make Mythos Preview generally available, so teams should not treat this as a normal near-term default model purchase.

Best Use Cases

Mythos Preview is best understood as a controlled frontier model for defensive security, autonomous software work, and long-running agents over large codebases or critical systems. It fits environments where the organization can justify a gated-research posture, strong internal review, and careful use boundaries.

It is not the right default for everyday assistant work, broad public product rollout, or casual experimentation. Anthropic’s own release posture makes that clear: this is a restricted model for organizations that can absorb both its capability upside and its safety burden.

Comparisons

• Claude Opus 4.6 (Anthropic): Opus is the public premium Claude route for hard coding and agentic work; Mythos Preview is the more restricted security-first research tier above that public surface.
• GPT-5.4 (OpenAI): GPT-5.4 remains the more broadly available frontier generalist, while Mythos Preview is positioned for narrower, higher-risk, cyber-heavy use.
• Gemini 3.1 Pro Preview (Google): Gemini is the more conventional preview frontier route for multimodal reasoning and agentic workflows; Mythos Preview differentiates through restricted access and unusually strong defensive-security framing.