Claude Opus
ModelsDefinition
The most capable Claude model tier, excelling at complex multi-step reasoning, nuanced analysis, and high-stakes creative tasks. Highest accuracy but most expensive and slowest. Best suited for tasks where output quality outweighs cost and latency concerns.
Example Usage
Use Opus for complex architectural analysis that requires deep multi-step reasoning, adversarial code review, or high-stakes document synthesis where a single wrong inference is costly.
Why It Matters for the CCA-F Exam
CCA-F Domain 1 (Model Selection & Routing) tests whether you can justify using Opus over cheaper tiers. Expect scenario questions where a candidate must identify which workloads warrant Opus-level cost — complex multi-step reasoning, nuanced judgment, and tasks where output quality directly drives business outcomes.
In Depth
What Makes Opus the "Most Capable" Tier
The Opus tier sits at the top of the Claude capability pyramid. Today's flagship is claude-opus-4-8, which ships with a 1M-token context window and up to 128K output tokens — the same context ceiling as Fable 5. What distinguishes Opus from the other tiers is not raw speed but *depth of reasoning*: it performs best on tasks where a single wrong inference cascades into a wrong answer, such as multi-hop logic, adversarial code review, and open-ended research synthesis.
When Opus Is the Right Choice
Opus justifies its higher cost when:
- Reasoning chains are long and branching — architectural design critiques, legal document analysis, or multi-file code audits where the model must track many constraints simultaneously.
- Output quality has direct cost of failure — a misdiagnosed security vulnerability or a faulty financial model is more expensive than the API cost delta.
- The task is rare but high-stakes — Opus is not the right default for every call in a loop; model routing strategies typically reserve Opus for escalations after a cheaper tier flags complexity.
In practice, a well-designed system uses Claude Haiku for classification and triage, Claude Sonnet for the bulk of productive work, and Opus only when the other tiers return low-confidence signals or the task is known to be Opus-class upfront.
Adaptive Thinking and Effort Control
On claude-opus-4-7, claude-opus-4-8, and newer models, the budget_tokens parameter has been removed — sending it returns HTTP 400. Reasoning depth is now controlled through adaptive thinking: set thinking: {type: "adaptive"} and optionally output_config: {effort: "high" | "xhigh" | "max"} to steer how much the model reasons before answering. The effort parameter has the biggest impact at the Opus tier, where extended reasoning is most valuable and the quality ceiling is highest. Sampling parameters (temperature, top_p) are also removed on Opus 4.7+ — behavior must be steered through prompting and structured outputs.
Full Cross-Tier Capability Comparison
The table below is the single canonical reference for all three Claude tiers. The Sonnet and Haiku pages summarize their own tier and link here for the full picture.
Routing Heuristic for Architects
A common exam scenario: a pipeline processes 10,000 documents per day. Using Opus for all of them is expensive and slow. The elegant solution is a two-stage route: Haiku scores each document on complexity (cheap, fast), and only documents above a threshold are forwarded to Opus. See Task Decomposition & Routing Strategies for the full pattern.
How It Compares
| Feature | Claude Opus | Claude Sonnet | Claude Haiku |
|---|---|---|---|
| Tier position | Top | Middle | Entry |
| Current model ID | claude-opus-4-8 | claude-sonnet-4-6 | claude-haiku-4-5 |
| Context window | 1M tokens | 1M tokens | 200K tokens |
| Max output tokens | 128K | 64K | 64K |
| Adaptive thinking | Yes (effort control) | Limited | No |
| Sampling params (temp/top_p) | Removed on 4.7+ | At most one (4.x only) | Supported |
| Cost | Highest | Mid | Lowest |
| Latency | Slowest | Balanced | Fastest |
| Recommended use | Complex, high-stakes | Most production workloads | High-volume, low-complexity |
Frequently Asked Questions
What is the current Claude Opus model ID I should use in production?
`claude-opus-4-8` is the current flagship Opus model. Do not append date suffixes to the alias — use the exact ID as-is. The previous `claude-opus-4-7` and `claude-opus-4-6` are still available but `claude-opus-4-8` is the recommended default for new work.
Can I still set budget_tokens on Opus to control how much it thinks?
No. `budget_tokens` is deprecated on Opus 4.6 and removed (returns HTTP 400) on Opus 4.7, 4.8, and Fable 5. Use `thinking: {type: "adaptive"}` combined with `output_config: {effort: "high" | "xhigh" | "max"}` to steer reasoning depth on current models.
How do I decide between Opus and Sonnet for a production pipeline?
Start with Sonnet as the default. Escalate to Opus only when Sonnet's output quality is measurably insufficient — for example, it fails an evaluator or returns low confidence on a complex multi-step task. A routing pattern where Haiku pre-screens complexity is often more cost-efficient than defaulting all calls to Opus.