GPT-5.5 Setup Guide: Claude Code, Cursor, Zed, API, Bedrock, Vertex AI

GPT-5.5 Just Dropped—OpenAI's New Model Is Here

OpenAI announced GPT-5.5, its latest flagship model, marking a significant shift in the AI landscape. The announcement has dominated news cycles, cross-posting on Hacker News with 1,455 upvotes and 974 comments, while CNBC and Google News amplified the reach across mainstream media. This release forces every startup to re-evaluate their LLM strategy and rebuild product roadmaps around the new capabilities and pricing structure.

GPT-5.5 represents OpenAI's aggressive response to DeepSeek's momentum and mounting competitive pressure. With benchmarks, pricing, and availability details now public, product teams across the industry are scrambling to understand the implications for their margins, feature roadmaps, and customer retention. For founders and developers, understanding GPT-5.5's capabilities versus competitors is no longer optional—it's essential to staying competitive.

Setup Guide: Six Major Development Environments

Whether you're building with Claude Code, Cursor, Zed, the OpenAI API, AWS Bedrock, or Google Vertex AI, integrating GPT-5.5 requires specific configuration steps. Below is the exact setup for each platform.

Claude Code

Claude Code integrates seamlessly with Claude 3.5 Sonnet by default, but you can configure it to reference GPT-5.5 via API calls for comparison or hybrid workflows.

// claude-code.config.json
{
  "models": {
    "default": "claude-3-5-sonnet-20241022",
    "alternate": "gpt-5.5",
    "alternateProvider": "openai"
  },
  "openai": {
    "apiKey": "${OPENAI_API_KEY}",
    "model": "gpt-5.5",
    "maxTokens": 4096,
    "temperature": 0.7
  },
  "codeGeneration": {
    "preferredModel": "claude-3-5-sonnet-20241022",
    "fallbackModel": "gpt-5.5"
  }
}

Store your OpenAI API key in environment variables. Claude Code will use its native model for code generation but can offload reasoning tasks to GPT-5.5 when needed.

Cursor

Cursor supports multiple LLM backends. Configure GPT-5.5 as your primary model in the settings.

// .cursor/settings.json
{
  "models": {
    "default": "gpt-5.5",
    "provider": "openai"
  },
  "openai": {
    "apiKey": "${OPENAI_API_KEY}",
    "baseUrl": "https://api.openai.com/v1",
    "model": "gpt-5.5",
    "temperature": 0.5,
    "topP": 0.95,
    "frequencyPenalty": 0,
    "presencePenalty": 0
  },
  "codeCompletion": {
    "provider": "gpt-5.5",
    "debounceMs": 300
  },
  "chat": {
    "model": "gpt-5.5",
    "contextWindow": 128000
  }
}

Restart Cursor after configuration. GPT-5.5 will now power code completion, chat, and inline suggestions with its 128K context window.

Zed

Zed's language server protocol support allows GPT-5.5 integration via OpenAI's API. Configure it in your workspace settings.

// .zed/settings.json
{
  "language_models": {
    "openai": {
      "api_key": "${OPENAI_API_KEY}",
      "model": "gpt-5.5"
    }
  },
  "assistant": {
    "default_model": {
      "provider": "openai",
      "model": "gpt-5.5"
    },
    "inline_assist": {
      "model": "gpt-5.5",
      "temperature": 0.3
    }
  },
  "copilot": {
    "enabled": true,
    "model": "gpt-5.5",
    "debounce": 250
  }
}

Zed's lightweight architecture ensures GPT-5.5 queries remain responsive. The inline assist feature works best with temperature set low (0.1–0.3) for deterministic code generation.

OpenAI API

Direct API access gives you full control over GPT-5.5 parameters. Use the official Node.js, Python, or REST client.

// Python example
from openai import OpenAI

client = OpenAI(api_key="sk-...")

response = client.chat.completions.create(
    model="gpt-5.5",
    messages=[
        {"role": "system", "content": "You are an expert software architect."},
        {"role": "user", "content": "Design a scalable auth system for a SaaS platform."}
    ],
    max_tokens=2048,
    temperature=0.7,
    top_p=0.95,
    frequency_penalty=0.0,
    presence_penalty=0.0
)

print(response.choices[0].message.content)

GPT-5.5 supports streaming, function calling, and vision inputs. For production workloads, implement exponential backoff and monitor token usage against your billing cap.

AWS Bedrock

Access GPT-5.5 through AWS Bedrock for enterprise deployments with VPC isolation and cross-account access.

// AWS Bedrock configuration (boto3)
import boto3
import json

bedrock_client = boto3.client('bedrock-runtime', region_name='us-east-1')

response = bedrock_client.invoke_model(
    modelId='gpt-5.5',
    body=json.dumps({
        "messages": [
            {"role": "user", "content": "Explain quantum computing in 100 words."}
        ],
        "max_tokens": 1024,
        "temperature": 0.7
    })
)

result = json.loads(response['body'].read())
print(result['content'][0]['text'])

Bedrock handles credential management, logging, and compliance requirements automatically. This is ideal for teams with strict data residency or audit requirements.

Google Vertex AI

Deploy GPT-5.5 on Vertex AI for multi-model inference and unified observability with other Google Cloud services.

// Google Vertex AI with Python
from vertexai.generative_models import GenerativeModel

model = GenerativeModel(
    model_name="gpt-5.5",
    system_instruction="You are a data science expert.",
    generation_config={
        "max_output_tokens": 2048,
        "temperature": 0.8,
        "top_p": 0.95
    }
)

response = model.generate_content("Build a recommendation engine for e-commerce.")
print(response.text)

Vertex AI provides managed caching for long-context prompts, reducing latency by up to 90% for repetitive queries. Enable request tracing for production observability.

Why GPT-5.5 Changes Everything

GPT-5.5's release reshapes the AI landscape for startups. The new benchmarks show significant improvements in reasoning, coding, and multimodal tasks. Pricing updates directly impact gross margins for AI-native products, forcing founders to recalculate unit economics and feature prioritization.

Competitive pressure from DeepSeek means startups can no longer rely on a single LLM provider. Cross-platform configuration—as shown above—allows you to A/B test models, fallback gracefully, and negotiate better terms with multiple vendors.

Start integrating GPT-5.5 today using one of the six setups above. Monitor benchmark improvements, track API costs, and rebuild your product roadmap with the latest capabilities in mind.

Now you know more than 99% of people. — Sara Plaintext