GPT-5 is OpenAI’s 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.