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Grok 4.1 Fast Reasoning

Grok 4.1 Fast Reasoning is xAI's reasoning-enabled Grok 4.1 Fast model optimized for agentic operations. It combines structured chain-of-thought reasoning with speed-optimized inference and a context window of 1M tokens for complex agent workflows.

ReasoningFile InputVision (Image)Tool UseImplicit Caching
index.ts
import { streamText } from 'ai'
const result = streamText({
model: 'xai/grok-4.1-fast-reasoning',
prompt: 'Why is the sky blue?'
})

Providers

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Provider
Context
Latency
Throughput
Input
Output
Cache
Web Search
Per Query
Capabilities
ZDR
No Training
Release Date
Google Vertex AI
Legal:Terms
Privacy
1M
1.9s
204tps
$0.20/M$0.50/M
Read:$0.05/M
Write:
07/09/2025