Skip to content
Log In
Sign Up
Dashboard

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?'
})
OverviewPlaygroundAboutProvidersThroughputLatencyUptimeStatusSimilarFAQ

Frequently Asked Questions

  • How does Grok 4.1 Fast Reasoning differ from the non-reasoning variant?

    Grok 4.1 Fast Reasoning generates chain-of-thought reasoning traces before making decisions, improving accuracy on complex tasks at the cost of additional latency and tokens. The non-reasoning variant produces direct responses for faster throughput.

  • What is the context window for Grok 4.1 Fast Reasoning?

    1M tokens, matching the non-reasoning variant. This supports extensive agent sessions with large tool schemas and conversation histories.

  • When should I use reasoning versus non-reasoning in my agent?

    Use reasoning for complex decisions where accuracy matters (planning, ambiguous situations, high-stakes tool calls). Use non-reasoning for routine operations where speed is more valuable than analytical depth.

  • What does Grok 4.1 Fast Reasoning cost?

    Check the pricing panel on this page for today's numbers. AI Gateway tracks rates across every provider that serves Grok 4.1 Fast Reasoning.

  • How do I authenticate with Grok 4.1 Fast Reasoning through Vercel AI Gateway?

    Use your Vercel AI Gateway API key with xai/grok-4.1-fast-reasoning as the model identifier. AI Gateway manages routing and authentication automatically.

  • Can I see the reasoning traces in the response?

    Yes. The chain-of-thought traces are included in the API response. You can inspect and log the model's reasoning for debugging and auditing.

  • Does Vercel AI Gateway support Zero Data Retention for Grok 4.1 Fast Reasoning?

    Yes, Zero Data Retention is available for this model. Zero Data Retention is offered on a per-provider basis. See https://vercel.com/docs/ai-gateway/capabilities/zdr for details.