Claude Opus 5 (Fast)

anthropic/claude-opus-5-fast · AnthropicUnmeasurable

Declared family: Claude
Declared tokenizer tag: Claude
Entered catalogue: 24 July 2026
Measurement: Deferred: measurement cost above the per-model cap
Evidence confidence: Unknown

What we checked

Four different kinds of evidence, and what each one showed

We checked	What we found	Where it came from
How it counts tokens	Not measured yet	we measured it
How its API is set up	Set up identically to 4 other listings, field for field	api_051e33bf
How much it can read and write	Reads up to 1,000,000 tokens at once, writes up to 128,000	its own listing
Whether it thinks before answering	Reasons when asked to, at max, xhigh, high, medium, low, high by default	its own listing

Declared record

What the catalogue claims about this model

Fast-mode variant of [Opus 5](/anthropic/claude-opus-5) - identical capabilities with higher output speed at 2x pricing relative to regular Opus 5. Learn more in Anthropic's docs: https://platform.claude.com/docs/en/build-with-claude/fast-mode

Modalities: text+image+file->text
Declared tokenizer: Claude
Prompt price: $10.0 / M tokens
Completion price: $50.0 / M tokens

Supported parameters

include_reasoningmax_tokensreasoningreasoning_effortresponse_formatstopstructured_outputstool_choicetoolsverbosity

defaults: {}

Catalogue entry

History

Every observation, kept as taken

24 July 2026Enters the OpenRouter catalogue declared as Claude.

* Claude Opus 5 (Fast) no longer appears in the OpenRouter catalogue, first absent from the snapshot of 3 September 2026. The record stays because the measurements above were real when they were taken and this address has been published.