GPT-5.5 Instant

OpenAIMCP Tool CallReasoning

openai/gpt-5.5-instantClosed API

Compact GPT model for low-latency assistance and high-volume workloads

Benchmark Pricing$5.00 / 1M in$30.00 / 1M out$0.50 cache read

Context: 400,000 tokens•Max Output: 128,000 tokens•Knowledge: 2025-12-01•Released: 2026-05-05

TECHNICAL SPECIFICATIONS

Context Window400,000400K tokens

Max Output128,000128K tokens

LicenseProprietaryCloud API only

Input Modalities

TextVisionPDF

Function / Tool CallingSupported (MCP Ready)

Structured OutputsGuaranteed Schema

MODEL CONTEXT PROTOCOL (MCP) READINESS

✓ GPT-5.5 Instant 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 400,000 tokens, this model can handle moderately large MCP tool definitions and multi-turn conversation logs comfortably.

API CALL INVOCATION EXAMPLE

// Example: Calling GPT-5.5 Instant via OpenAI SDK
import OpenAI from "openai";

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

const response = await client.chat.completions.create({
  model: "openai/gpt-5.5-instant",
  messages: [{ role: "user", content: "Hello! Can you inspect MCP tools?" }],
});

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