| We checked | What we found | Where it came from |
|---|---|---|
| How it counts tokens | Not measured yet | we measured it |
| How its API is set up | Set up identically to 11 other listings, field for field | api_6c8e2afa |
| How much it can read and write | Reads up to 1,050,000 tokens at once, writes up to 128,000 | its own listing |
| Whether it thinks before answering | Reasons when asked to, at max, xhigh, high, medium, low, none, medium by default | its own listing |
| Who served our requests | OpenAI | we measured it, 5 October 2026 |
We sent OpenAI: GPT-5.6 Luna Pro fifty short pieces of text and recorded what each one cost it in tokens. The bars below are those costs. Two models built on the same tokenizer produce the same bars; a model built on a different one produces a different set, which is what makes this a fingerprint.
An x marks a row excluded as corrupt (caching or provider interference detected during measurement). Overhead subtracted: 1549 prompt tokens.
GPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. **Cost note:** pro mode spends far more...
Supported parameters
include_reasoningmax_completion_tokensmax_tokensreasoningreasoning_effortresponse_formatseedstructured_outputstool_choicetoolsverbosity
defaults: {"temperature":null,"top_p":null,"top_k":null,"frequency_penalty":null,"presence_penalty":null,"repetition_penalty":null}
