1. Optimized for Long-Horizon Coding Tasks

• OpenAI describes GPT-5.2 Codex as a highly intelligent coding model built for long-horizon, agentic coding work.
• Well suited to planning, refactoring, debugging, and multi-step implementation flows inside real codebases.

2. Adjustable Reasoning for Coding Work

• Supports configurable reasoning effort from low to xhigh depending on speed and quality needs.
• Accepts both text and image inputs while producing text output.

3. Large Context + Long Output

• 400 k token context window supports broad repository understanding and larger working sets.
• Allows up to 128 k output tokens for longer patches, code generation, and technical explanations.

4. Up-to-Date Model Snapshot

• Knowledge cut-off of Aug 31 2025 keeps it current with newer tools and frameworks.
• Supports streaming, function calling, and structured outputs for tool-driven coding workflows.

1. Fast, Lightweight, and Cost-Efficient

• Designed for speed with low latency, making it ideal for high-volume, real-time applications.
• More affordable than larger GPT-4.1 and GPT-5 models, enabling scalable deployments.

2. Strong Instruction Following

• Excels at following structured instructions and producing concise, deterministic outputs.
• Suitable for assistants, command-style interfaces, and tools that require stable, predictable behavior.

3. Reliable Tool Calling & Structured Outputs

• Built with strong support for:
  • Function calling
  • Structured outputs (JSON, typed objects)
  • Systematic workflows
• Ideal for automation, reasoning over parameters, and multi-step tool pipelines.

4. Multimodal Input (Text + Image)

• Accepts both text and image as input.
• Useful for tasks such as:
  • Image captioning
  • UI element reading
  • Visual question answering

5. Text-Only Output for Clarity

• Outputs text only, ensuring clean and consistent results for:
  • Data extraction
  • Summaries
  • Code comments
  • Chat responses

6. Massive 1M-Token Context Window

• Supports 1,047,576 tokens, enabling:
  • Long documents or books
  • Large codebases
  • Extensive conversation memory
• Great for long-context reasoning without requiring chunking.

7. Practical for Everyday AI Applications

• Sweet spot for:
  • Customer support agents
  • Content rewriting
  • Lightweight analysis
  • Classification and tagging
  • Workflow assistants
• Recommended primarily for simpler use cases, with GPT-5 Mini suggested for more complex tasks.

8. Broad API Support

• Available across:
  • Chat Completions
  • Responses
  • Realtime
  • Assistants
  • Other major API endpoints
• Compatible with long-context modes for large-scale retrieval and processing.