GPT-5.6 Luna
GPT-5.6 Luna is the smallest and lowest-cost model in OpenAI's GPT-5.6 family. Use it for high-volume, latency-sensitive, or cost-sensitive agent work where Sol or Terra would be more than you need.
Strengths
- Lowest GPT-5.6 pricing; good for prototyping, subagents, and high-volume loops.
- Fast responses relative to larger GPT-5.6 variants.
- Same family tool-calling and agent support as Sol and Terra.
Limitations
- Not a frontier model. For harder problems where peak intelligence matters, GPT-5.6 Sol or GPT-5.6 Terra is the better pick.
- Smaller capacity for long, open-ended reasoning chains.
Tools
GPT-5.6 Luna has access to all agent tools when used with Cursor including:
Find files by name, read directory structures, and grep for patterns.
Generate search queries and fetch results from the web.
Read file contents, including images for vision-capable models.
Suggest edits and apply them automatically.
Execute terminal commands and monitor output.
Control a browser to take screenshots, test applications, and verify visual changes. See the Browser documentation.
Generate images from text descriptions or reference images.
Ask clarifying questions while continuing to work in the background.
Retrieve rules based on type and description.
Learn more about how tools work and tool calling fundamentals.
Pricing
GPT-5.6 Luna is a third-party model, so it isn't part of the usage included with Cursor plans. On The X Subscription it's billed at the rates below from your prepaid credit. On legacy Cursor plans it draws from the Other Models pool. All prices are per million tokens.
| Name | ||||
|---|---|---|---|---|
| $0.2 | $0.25 | $0.02 | $1.2 | |
| $0.4 | $0.5 | $0.04 | $2.4 | |
| $0.4 | $0.5 | $0.04 | $1.8 | |
| $0.8 | $1 | $0.08 | $3.6 |
A Fast mode tier (gpt-5.6-luna-fast) is available for priority processing at 2x the standard rates.
When input exceeds 272k tokens (long context), input pricing doubles and output pricing is 1.5x the standard rate. The same multipliers apply in Fast mode: long-context requests bill at 2x the Fast input, cache write, and cache read rates, and 1.5x the Fast output rate.