1. Highest reasoning quality in the GPT-5 family

• Uses significantly more compute to "think harder" before responding.
• Designed for the toughest reasoning tasks where answer quality matters more than speed.
• Produces more precise, reliable, and detailed outputs than standard GPT-5.

2. Advanced multi-turn reasoning via Responses API

• Available only in the Responses API to support:
  • Multi-turn internal model interactions before returning a reply.
  • Advanced control patterns (e.g., background mode for long-running jobs).
• Ideal for complex workflows, deep planning, and multi-step analysis.

3. Configured for maximum effort by default

• Always runs with reasoning.effort: 'high' (no lower-effort mode).
• Prioritizes depth and correctness over latency and cost.

4. Multimodal input

• Accepts text + image as input.
• Outputs text, with strong instruction-following and analysis capabilities.

5. Tooling and ecosystem integration

• Supports Web Search, File Search, and Image Generation (as tools).
• Supports MCP and other Responses API tooling patterns.
• Does not support Code Interpreter and does not support Computer Use, keeping focus on pure reasoning + tools.

1. High-intelligence small reasoning model

• Delivers strong reasoning performance in a compact footprint.
• Ideal for tasks that need intelligence but must stay cost-efficient.

2. Excellent for developer workflows

• Supports Structured Outputs, function calling, and Batch API.
• Reliable for backend automation, agents, and data-processing pipelines.

3. Strong text reasoning capabilities

• Handles multi-step logic, natural language analysis, SQL translation, entity extraction, and content generation.
• Works well for landing pages, policy summaries, and knowledge extraction (as shown in built-in examples).

4. 200K context window

• Allows large documents, multi-step analysis, and long-running conversations.
• Reduces the need for aggressive chunking or external retrieval systems.

5. High 100K-token output limit

• Enables long explanations, multi-section documents, or detailed reasoning sequences.

6. Pure text-focused model

• Input/output is text-only (no image or audio support).
• Optimized for language-heavy reasoning and logic tasks.

7. Broad API compatibility

• Works across Chat Completions, Responses, Realtime, Assistants, Embeddings, Image APIs (as tools), and more.
• Supports streaming, function calling, and structured outputs.

8. Cost-efficient for production at scale

• Same cost/performance profile as o1-mini but with higher intelligence.