Claude Capybara Tier Explained: Anthropic’s 4-Level Model System
Anthropic now has four model tiers for Claude, and the Capybara tier sits at the very top. Revealed through a data leak in March 2026, Capybara introduces Claude Mythos as its first model — a system that scores dramatically higher than Opus 4.6 across coding, reasoning, and cybersecurity benchmarks.
This guide explains what each tier does, how they compare, and how to choose the right one for your use case. If you already use the Claude API, switching to Capybara will require changing a single parameter.
What Is a Tier in Claude’s System
A tier is a capability class that defines the trade-off between speed, intelligence, and cost. Anthropic groups its models into tiers rather than just version numbers because each tier serves fundamentally different purposes.
Tiers vs Models
A tier is not a model. Opus is a tier; Claude Opus 4.6 is a model within that tier. Similarly, Capybara is a tier, and Claude Mythos is the specific model released within it. Anthropic can release multiple model versions within the same tier over time, just as they’ve done with Opus (4.5, 4.6).
This distinction matters because it tells you about the model’s fundamental design philosophy, not just its version number. A new tier signals a qualitative jump in what the AI can do, while a new version within an existing tier represents incremental improvement.
The Original Three Tiers
Before March 2026, Claude had three tiers, all named after literary and musical concepts:
Haiku — the smallest, fastest, and cheapest. Named after the brief Japanese poetry form, it handles lightweight tasks with minimal latency. Think of it as the quick-response tier for high-volume applications.
Sonnet — the balanced middle ground. Named after the 14-line poem, it offers strong capability at a reasonable price. This is what most developers use for everyday coding assistance and content tasks.
Opus — the flagship. Named after a major musical composition, it was Anthropic’s most powerful tier until Capybara arrived. Opus handles complex reasoning, deep research, and difficult technical problems.
Where Capybara Fits in the Hierarchy
The Capybara tier doesn’t replace Opus — it adds a new level on top. The four-tier system now looks like this:
| Tier | Current Model | Speed | Reasoning | Coding | Cybersecurity | Cost |
|---|---|---|---|---|---|---|
| Haiku | Claude Haiku 4.5 | Fastest | Basic | Good | Limited | $ |
| Sonnet | Claude Sonnet 4.6 | Fast | Strong | Strong | Moderate | $$ |
| Opus | Claude Opus 4.6 | Moderate | Excellent | Excellent | Good | $$$ |
| Capybara | Claude Mythos | Slowest | Breakthrough | Breakthrough | Far ahead | $$$$ |
Why the Name “Capybara”
The shift from literary names to an animal is deliberate. The capybara — Earth’s largest rodent — is unexpectedly large and capable despite its gentle appearance. Anthropic chose this name to signal that the Capybara tier represents a fundamentally different capability class, not just a bigger version of Opus.
Previous tier names (Haiku, Sonnet, Opus) suggested increasing scale within a known framework. Capybara breaks that pattern to communicate that this tier is something new entirely.
Why Anthropic Needed a Fourth Tier
The performance gap between Claude Mythos and Opus 4.6 is too large for a version number. Calling it “Opus 5.0” would understate the difference and confuse the pricing structure. A new tier communicates two things clearly: the capability jump is qualitative rather than quantitative, and the cost will be substantially higher.
One competitor blog described the difference as “taking an elevator versus climbing stairs” from Opus to Capybara. The tier system preserves Opus as a valuable option while giving the breakthrough model its own positioning.
What Each Tier Is Best For
Choosing the right tier is about matching your task to the minimum capability that handles it well. Using Capybara for a simple text classification task wastes money; using Haiku for a complex security audit wastes time.
Haiku 4.5: Speed and Volume
Haiku is designed for tasks where response time and cost matter more than deep reasoning. It handles text classification, content tagging, simple summarization, real-time chatbot responses, and high-concurrency lightweight operations.
Best for: Applications processing thousands of simple requests per minute. If your task has a straightforward answer and doesn’t require multi-step reasoning, Haiku delivers it fastest and cheapest.
Sonnet 4.6: The Balanced Choice
Sonnet is where most developers should start. It offers strong programming assistance, content creation and editing, data analysis with reporting, and medium-complexity reasoning tasks. Sonnet 4.6 provides the best cost-to-performance ratio in the Claude lineup.
Best for: Daily development work, writing assistance, moderate analytical tasks. If you’re building an AI-powered product and need reliable quality without premium pricing, Sonnet is the default answer. Our pricing expectations guide explores this in depth.
Opus 4.6: Complex Reasoning
Opus handles what Sonnet cannot: complex code architecture design, in-depth research across multiple domains, long-form translation requiring nuanced understanding, and difficult mathematical and scientific reasoning. It was the flagship tier until Capybara’s arrival and remains the right choice for 95% of complex professional tasks.
Best for: Senior-level engineering problems, academic research, strategic analysis. Use Opus when the quality of reasoning directly impacts the value of the output.
Capybara (Mythos): Breakthrough Applications
Based on leaked documentation, the Capybara tier targets six specific capability areas:
- Automated vulnerability discovery — proactive identification of security weaknesses at scale
- Ultra-difficult multi-step reasoning — problems that require synthesizing information across many domains
- Large codebase refactoring — architectural changes across massive repositories
- Enterprise security audits — comprehensive analysis of complex system attack surfaces
- Advanced agent workflows — autonomous multi-step task execution with high consistency
- Zero-day identification — finding previously unknown vulnerabilities in software
Best for: Frontier applications where the capability improvement justifies the premium cost. Most developers will not need this tier for everyday work, but for organizations dealing with critical security or reasoning challenges, it represents a step change.
Capybara’s Core Capabilities
The leaked documentation provides specific details about how Capybara differs from Opus beyond just benchmark scores.
Coding and Reasoning
Claude Opus 4.6 already scores 80.8% on SWE-Bench and 65.4% on Terminal-Bench 2.0, leading or matching GPT-5.4 on most coding benchmarks. Capybara reportedly scores “dramatically higher” across all these tests.
The improvement isn’t just about solving more problems correctly. The leaked materials describe the ability to “create deep connective tissue between ideas and knowledge” — suggesting architectural innovations in cross-domain reasoning rather than simple accuracy improvements. This means Capybara can potentially see connections between disparate fields that current models miss.
Cybersecurity: The Defining Feature
Cybersecurity is what separates Capybara from a hypothetical “Opus 5.0.” Anthropic’s internal assessment states the model is “currently far ahead of any other AI model in cyber capabilities” and warns it “presages an upcoming wave of models that can exploit vulnerabilities in ways that far outpace the efforts of defenders.”
This capability is precisely why Anthropic created a new tier rather than a version update. The cybersecurity implications required a different release strategy, different pricing, and different access controls than any previous Claude model.
Agent Workflows
The Capybara tier shows enhanced consistency in autonomous multi-step task execution. While Claude Opus 4.6 can run agent workflows through Claude Code, Capybara’s improvements mean fewer failures in long chains of actions and better judgment about when to proceed versus when to pause for human input.
Pricing and Cost Strategy
No official Capybara pricing has been announced, but the tier structure gives strong signals about where it will land.
Expected Pricing
For reference, here are current Claude API prices:
| Tier | Input (per M tokens) | Output (per M tokens) |
|---|---|---|
| Haiku 4.5 | $0.80 | $4.00 |
| Sonnet 4.6 | $3.00 | $15.00 |
| Opus 4.6 | $15.00 | $75.00 |
| Capybara | TBD (est. $30-75) | TBD (est. $150-375) |
Community estimates range from 2-3x Opus pricing (conservative) to 4-5x (aggressive). Anthropic confirmed the model is “expensive to run,” which aligns with the higher end of these estimates.
How to Manage Capybara Costs
Three strategies will matter when Capybara becomes available:
Tiered routing sends each request to the cheapest tier that can handle it. Simple queries go to Haiku, standard work to Sonnet, complex tasks to Opus, and only truly breakthrough problems to Capybara.
Prompt Caching reduces costs for repeated prompt prefixes. If your application sends the same system prompt with different user queries, cached tokens cost significantly less.
Batch API provides a 50% discount for non-real-time processing. If your Capybara workload doesn’t need instant responses, batch processing cuts the cost roughly in half.
How to Access Capybara via the API
The Claude API uses a unified interface across all tiers. Switching to Capybara when it becomes available will require changing exactly one parameter.
Unified API Interface
from anthropic import Anthropic
client = Anthropic()
# Current: using Opus
response = client.messages.create(
model="claude-opus-4-6-20250205",
max_tokens=4096,
messages=[{"role": "user", "content": "Your prompt"}]
)
# Future: switching to Capybara (when available)
response = client.messages.create(
model="claude-capybara-mythos", # just change this line
max_tokens=4096,
messages=[{"role": "user", "content": "Your prompt"}]
)No SDK changes, no code restructuring, no migration. The Anthropic SDK handles all tiers identically.
Current Access Status
As of March 2026, the Capybara tier is in restricted early testing with select cybersecurity defense organizations. No public API access exists yet.
Expected timeline: expanded testing through Q2 2026, possible limited beta in Q3, and general availability potentially in October 2026 — aligned with Anthropic’s expected IPO at a valuation exceeding $60 billion.
Questions About Claude Capybara Tier
What is the Capybara tier in Claude?
The Capybara tier is the fourth and highest level in Anthropic’s Claude model hierarchy, positioned above Opus. It represents a breakthrough capability class, with Claude Mythos as its first model, offering dramatically higher performance in coding, reasoning, and cybersecurity.
How many tiers does Claude have now?
Four tiers: Haiku (fastest and cheapest), Sonnet (balanced performance and cost), Opus (flagship for complex tasks), and Capybara (breakthrough for frontier applications). Each tier serves different use cases.
Is Capybara better than Opus?
Yes, across every measured dimension according to leaked benchmarks. However, it will be significantly more expensive and is not yet publicly available. For most professional tasks, Opus 4.6 remains the practical choice.
Which Claude tier should I use?
Start with Sonnet 4.6 for general work. Move to Opus for complex reasoning and architecture tasks. Use Haiku for high-volume simple operations. Reserve Capybara for breakthrough-level challenges when it becomes available.
How much will the Capybara tier cost?
No official pricing has been announced. Community estimates range from 2-3x to 4-5x current Opus pricing. Batch API and prompt caching will help manage costs.
What is the difference between Capybara and Claude Mythos?
Capybara is the tier name — a capability class. Claude Mythos is the specific model within that tier. Future models may also be released under the Capybara tier with different names.
Can I use Capybara right now?
No. It is in restricted early testing with cybersecurity defense organizations. Public availability is expected late 2026, potentially October.