OpenAI Brings GPT-5.6 to the API with Sol, Terra, and Luna
OpenAI has begun rolling out GPT-5.6 in the API in three variants: Sol, Terra, and Luna. Sol is positioned as the flagship model for programming, complex intellectual work, cybersecurity, and scientific tasks; Terra is intended to deliver a performance level close to GPT-5.5 but at a lower cost; Luna is designed for fast, inexpensive tasks involving large volumes of data.
The company is emphasizing efficiency: GPT-5.6 is expected to use fewer tokens and complete agentic tasks faster. In the Artificial Analysis benchmark for coding agents, the Sol version with maximum reasoning, according to OpenAI, set a record score of 80 points while using fewer output tokens and completing tasks faster than previous solutions.
The main new API capabilities are programmatic tool calling and multi-agent. The model can write and run JavaScript to control tool chains, as well as create parallel subagents within a single request. This should help break complex tasks into parts, compare different approaches, and assemble the final response with fewer model calls.
Why it matters
- —GPT-5.6 expands OpenAI’s model lineup for different scenarios, from expensive complex tasks to fast high-volume requests.
- —New agentic features may reduce the number of steps and tokens in complex developer workflows.
- —Stronger safety checks show that powerful models for cybersecurity and biology will operate with additional restrictions.
Key facts
- GPT-5.6 is launching in the OpenAI API in three variants: Sol, Terra, and Luna.
- Sol is positioned as the flagship model for code, complex reasoning, cybersecurity, and science.
- Terra is focused on GPT-5.5-level performance at a lower cost, while Luna is focused on speed and accessibility.
- Programmatic Tool Calling is available in the Responses API and lets the model write and run JavaScript to control tools.
- Multi-agent is initially launching in beta and enables parallel subagents to be created within a single request.
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