GPT-5 Quickstart Guide GPT-5 is our most capable model to date, designed for advanced reasoning, code generation, instruction following, and tool use. This guide covers key features and how to get the most from the GPT-5 family.

🧠 Model Variants gpt-5: Best for complex, multi-step tasks and rich world knowledge.

gpt-5-mini: Balanced speed and cost, ideal for chat and medium-difficulty reasoning.

gpt-5-nano: Lightweight, great for fast, simple tasks like classification.

🔧 Key Features Reasoning Effort Control how deeply the model thinks before responding.

minimal: Fastest; good for coding and clear instructions.

medium (default): Balanced.

high: Most thorough.

Prompt tip: For minimal, ask the model to “think step-by-step” to improve quality.

Verbosity Control how much the model says.

low: Concise answers/code (e.g., SQL queries).

medium: Default.

high: Detailed explanations or refactoring.

Custom Tools Define tools with freeform text input (code, SQL, etc.). Use grammars (CFGs) to constrain output to specific formats. Always validate inputs/outputs.

Allowed Tools Control which tools the model can or must use via allowed_tools. Helps with safety, predictability, and caching.

Preambles Ask the model to explain tool usage decisions before invoking them. Improves transparency and debugging.

🔄 Migration Tips From older models: Use gpt-5 for o3 and gpt-4.1 tasks. Start with medium or minimal reasoning depending on complexity.

From Chat Completions: Switch to the Responses API to support reasoning carryover (CoT). This improves latency and cache hits.

💻 Best Practices Coding Define the model’s role clearly.

Require testing/validation for generated code.

Use examples for tool usage.

Guide formatting with Markdown standards.

Frontend Development Supports Tailwind, shadcn/ui, Radix Themes, Lucide icons, Motion.

Use detailed prompts for better UI/UX, structure, and integration.

Agentic Tasks Ask GPT-5 to break down tasks and persist until fully resolved.

Use preambles and TODO tools to improve planning and completeness.

🧩 Reasoning Tokens GPT-5 retains and reuses reasoning across turns for improved performance. With ZDR or store=false, encrypted reasoning is supported for secure reuse.