Grok 4.1 Fast

xAIMCP Tool Call

xai/grok-4.1-fastClosed API

xAI's fast agentic tool-calling model with a 2M context window; non-reasoning variant for low-latency responses

Benchmark Pricing$0.20 / 1M in$0.50 / 1M out$0.05 cache read

Context: 2,000,000 tokens•Max Output: 30,000 tokens•Released: 2025-11-19

TECHNICAL SPECIFICATIONS

Context Window2,000,0002M tokens

Max Output30,00030K tokens

LicenseProprietaryCloud API only

Input Modalities

TextVision

Function / Tool CallingSupported (MCP Ready)

Structured OutputsGuaranteed Schema

MODEL CONTEXT PROTOCOL (MCP) READINESS

✓ Grok 4.1 Fast natively supports OpenAI / Anthropic format tool calling and is fully compatible with MCP servers and agent loops.

MCP Context Window Recommendations

With a context capacity of 2,000,000 tokens, this model can handle extremely large MCP resource manifests, complete database schemas, and multiple active server tool definitions simultaneously without degradation.

API CALL INVOCATION EXAMPLE

// Example: Calling Grok 4.1 Fast via OpenAI SDK
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.XAI_API_KEY,
});

const response = await client.chat.completions.create({
  model: "xai/grok-4.1-fast",
  messages: [{ role: "user", content: "Hello! Can you inspect MCP tools?" }],
});

console.log(response.choices[0].message.content);