OpenAI's efficient reasoning model for focused high-volume work, extraction, and frequent automation, with million-token context, vision, and tool support.
OpenAI
| Item | Specification |
|---|---|
| Input | Text, images |
| Output | Text |
| Context | 1,050,000 tokens |
| Max Output | 128,000 tokens |
| Vision | ✓ Supported |
| Function Calling | ✓ Supported in full through the Responses API; available in Chat Completions only with reasoning_effort: none |
GPT-6 Luna is an efficient reasoning model released by OpenAI on September 22, 2026. Its API identifier is gpt-6-luna. It accepts text and image input, produces text, provides a 1,050,000-token context window with up to 128,000 output tokens, and has a knowledge cutoff of May 18, 2026.
The model is designed for focused, frequently repeated work at scale, including extraction, classification, triage, fine-grained editing, and routine automation. It offers six reasoning-effort levels from none through max and uses the Responses API for function calling, web search, file search, Code Interpreter, hosted shell, Computer Use, MCP, and other tools. The GPT-6 family also supports asynchronous tool calls and mid-turn steering.
none, low, medium, high, xhigh, or max to control processing depth.| Feature | Benefit |
|---|---|
| Efficiency-Focused Design | Fits well-defined workloads that run frequently and require stable repeated execution. |
| 1.05M Context Window | Processes large record sets, long documents, and cross-file information with less frequent slicing. |
| 128K Output Limit | Supports long lists, batch transformations, code, and large structured responses. |
| Six Reasoning Levels | Keeps routine work direct while adding depth for harder but constrained problems. |
| Responses API Tooling | Connects natively to search, files, code execution, shell, Computer Use, MCP, and related capabilities. |
| Async Calls and Mid-Turn Steering | Advances independent tool tasks in parallel and accepts new priorities or constraints during execution. |
Start with none or low for classification, extraction, format conversion, and fine-grained edits. Use medium when a task coordinates several constraints or updates, then test high, xhigh, or max for harder bounded problems. A fixed evaluation set provides the best basis for selecting the level.
Define every field, allowed value, counterexample, and output schema, then divide large batches into independently retryable units. Use Structured Outputs or strict function parameters and add automated checks for missing values, malformed inputs, and boundary cases.
Group material by source, time, or record type and distinguish instructions, evidence, and data to process. Even with a 1.05M-token window, retrieval, deduplication, and sample review remain useful because irrelevant context can reduce batch consistency.
Start with GPT-6 Luna for focused, frequently repeated extraction, classification, editing, and automation work. GPT-6 Sol is better aligned with complex coding, open-ended analysis, professional judgment, and demanding agent workflows; choose using production-like samples for quality, tool success, and latency.
GPT-6 Luna is available on LinkModel. Open its live model page, copy the published model ID, and submit text or image input with the request structure currently shown there. Use the live page for the platform route, accepted parameters, and available tools instead of substituting the OpenAI API identifier.
Complete a basic text request with the model ID shown on LinkModel, then use a representative batch to test structured outputs, image input, long context, and tool calls. Check field consistency, truncation, errors, concurrent stability, and retry results, and confirm which options LinkModel currently exposes for reasoning_effort, asynchronous tool calls, and mid-turn steering.
Tiered by input prompt tokens (incl. cache): once over the threshold, the whole request is billed at the higher tier.
| Token Type | Short context ≤272K | Long context >272K |
|---|---|---|
| Input | $0.075$0.1-25% | $0.15$0.2-25% |
| Output | $0.375$0.5-25% | $0.5625$0.75-25% |
| Cached input | $0.0075$0.01-25% | $0.015$0.02-25% |
| Cache write | $0.09375$0.125-25% | $0.1875$0.25-25% |