Is Claude Opus 4.5 available on FastMetal?

Not at the moment. Claude Sonnet 5, from the same lab, is available on the FastMetal API today.

What is the context window of Claude Opus 4.5?

200,000 tokens, shared between the prompt and the response.

How does Claude Opus 4.5 rank?

#38 on the public arena's Japanese board (ELO 1,441). Ranks move as the leaderboard is updated.

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anthropic/claude-opus-4-5

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Claude Opus 4.5

Claude Opus 4.5 is Anthropic’s frontier reasoning model optimized for complex software engineering, agentic workflows, and long-horizon computer use. It offers strong multimodal capabilities, competitive performance across real-world coding and reasoning benchmarks, and improved robustness to prompt injection. The model is designed to operate efficiently across varied effort levels, enabling developers to trade off speed, depth, and token usage depending on task requirements. It comes with a new parameter to control token efficiency, which can be accessed using the OpenRouter Verbosity parameter with low, medium, or high. Opus 4.5 supports advanced tool use, extended context management, and coordinated multi-agent setups, making it well-suited for autonomous research, debugging, multi-step planning, and spreadsheet/browser manipulation. It delivers substantial gains in structured reasoning, execution reliability, and alignment compared to prior Opus generations, while reducing token overhead and improving performance on long-running tasks.

11/24/2025

200,000 tokens

#21 Text (Coding)

Specifications

Modalities

Input

file

image

text

Output

text

Supported Parameters

include_reasoning

max_tokens

reasoning

response_format

stop

structured_outputs

temperature

tool_choice

tools

top_k

verbosity

Max Output Tokens

64,000

Frequently asked questions

Is Claude Opus 4.5 available on FastMetal?: Not at the moment. Claude Sonnet 5, from the same lab, is available on the FastMetal API today.
What is the context window of Claude Opus 4.5?: 200,000 tokens, shared between the prompt and the response.
How does Claude Opus 4.5 rank?: #38 on the public arena's Japanese board (ELO 1,441). Ranks move as the leaderboard is updated.