Claude Opus 4.8

Technical Specifications of Claude Opus 4.8

What is Claude Opus 4.8?

Claude Opus 4.8 is Anthropic’s flagship generally available reasoning model focused on high-autonomy agent workflows, large-scale software engineering, professional analysis, and long-context reasoning. It builds on Claude Opus 4.7 with improved coding reliability, better tool orchestration, stronger judgment, and significantly improved honesty behaviors.

Anthropic positions Opus 4.8 as a hybrid reasoning model capable of sustained autonomous execution over long-running workflows. The model is optimized for complex multi-step coding, research, financial analysis, legal reasoning, and enterprise AI agents.

Main Features of Claude Opus 4.8

• 1M-token context window: Opus 4.8 can reason across enormous repositories, long technical documents, and enterprise knowledge bases without losing context.
• Long-horizon agentic coding: Anthropic specifically optimized the model for autonomous engineering tasks including repository-scale migrations, debugging, tool orchestration, and multi-file refactoring.
• Adaptive effort control: Users can dynamically adjust how much reasoning compute Claude applies to a task, balancing latency, quality, and token usage.
• Dynamic workflows: Claude Code can now orchestrate hundreds of parallel subagents within a single session, enabling large-scale autonomous execution pipelines.
• Improved honesty and uncertainty awareness: Anthropic reports that Opus 4.8 is approximately four times less likely than Opus 4.7 to ignore flaws in generated code or falsely claim progress.
• Higher-quality tool usage: Cursor, Devin, and enterprise partners report more efficient tool calling, stronger instruction following, and better long-session reliability.

Benchmark Performance of Claude Opus 4.8

Anthropic reports major gains across agentic coding, browser automation, and professional reasoning benchmarks:

• Online-Mind2Web: ~84% score for browser-agent tasks, outperforming prior Opus releases and reportedly ahead of GPT-5.5 in Anthropic’s internal evaluation setup.
• Legal Agent Benchmark: First model reported to exceed 10% on the all-pass legal-agent standard.
• CursorBench: Improved performance across all effort levels with more efficient tool usage and fewer redundant actions.
• Terminal-Bench 2.1: Strong gains in terminal-based agent workflows and long-running coding tasks.
• Enterprise knowledge work: Databricks, Hebbia, and legal AI partners reported better retrieval precision, deeper analysis quality, and stronger structured output generation.

Claude Opus 4.8 vs Other Frontier Models

Limitations of Claude Opus 4.8

• Very large-context and high-effort modes can consume substantial tokens and increase inference costs.
• Some developers report mixed real-world gains versus Opus 4.6 and 4.7 in independent testing.
• The new system-message format introduced compatibility issues for some OpenAI-compatible routers and proxy layers.
• Anthropic acknowledges that Mythos-class systems will surpass Opus 4.8 in advanced reasoning and cybersecurity capability.

Representative Enterprise Use Cases

1. Repository-scale code migrations
2. Autonomous software engineering agents
3. Financial document analysis
4. Legal research and drafting
5. Deep enterprise knowledge retrieval
6. Browser automation agents
7. Multi-step DevOps orchestration
8. Long-form technical research
9. Structured business intelligence workflows

How to Access Claude Opus 4.8 in CometAPI

Step 1: Get API Access

Create an account at CometAPI Console and get API a key .

Step 2: Use the Model ID

Use the following API model identifier:

claude-opus-4-8/ claude-opus-4-8-thinking

Step 3: Configure Effort Levels

Choose reasoning effort settings depending on latency and quality requirements:

• low
• high
• extra (xhigh)
• max

Higher effort settings improve deep reasoning and autonomous execution quality but increase token usage.

​ Developer Documentation

• Quick Integration Guide (OpenAI Format)
• Native Messages Parameter Reference