Claude Opus 4.8

Model Overview

Claude Opus 4.8 is a flagship model from Anthropic, released on May 28, 2026. Prior to the release of the newer Fable 5, Opus 4.8 served as Anthropic's primary frontier model, specifically optimized for agentic workflows, complex coding tasks, and enterprise-grade reasoning. It features a massive 1-million-token context window and a 128,000-token output limit, handling text, image, and PDF inputs.

Capabilities

• Deep Sustained Reasoning: Designed to excel at complex reasoning and deep technical analysis.
• Agentic Performance: State-of-the-art capability for "computer use" and long-running, multi-step browser-agent workflows, including codebase-scale migrations.
• Effort Control & Fast Mode: Allows users to adjust "effort" to balance speed, reasoning depth, and cost, alongside a Fast mode offering 2.5x standard operation speeds.
• Honesty & Reliability: Approximately four times less likely than its predecessor (Opus 4.7) to allow flawed code to pass without flagging potential issues.

Example Use Cases

• Large-scale software engineering projects and codebase migrations.
• Deep financial and scientific data analysis across massive document datasets.
• Orchestrating hundreds of parallel subagents for complex enterprise workflows.
• Advanced mathematical and logical problem-solving requiring sustained attention.

Performance & Benchmarks

While specific numerical benchmark scores are not fully detailed in the current dataset, Opus 4.8 is highly recognized for its robust performance in agentic reasoning. Its self-verification capabilities and reduced overconfidence significantly improve its effective real-world task completion rate compared to earlier models.

Intended Use & Limitations

Claude Opus 4.8 is intended for enterprise environments, researchers, and developers requiring maximum reasoning power and long-context analysis. Its "high" default effort setting may make it more expensive than mid-tier models (like the Sonnet line) for simple, everyday queries. Note that as of mid-2026, it has been largely superseded by newer generation models like Claude Fable 5.

About Anthropic

Anthropic is an AI safety and research company focused on building reliable, interpretable, and steerable AI systems. They are the creators of the Claude family of models, known for prioritizing safety and alignment alongside frontier capability.