GPT-5.6 Luna vs. Claude Haiku 5.5

GPT-5.6 Luna is the lowest-cost model in OpenAI’s GPT-5.6 family, built for fast and affordable AI assistance across everyday and technical workflows. The GPT-5.6 lineup includes Sol as the flagship model, Terra as the balanced model for everyday work, and Luna as the efficient model for users who need strong capability at lower cost. Luna is intended for developers, businesses, and teams that need scalable AI for coding help, workflow automation, research support, analysis, customer-facing applications, and high-volume API usage. In the pasted preview text, Luna is presented as part of the same GPT-5.6 release process and benchmark set as Sol and Terra. It appears in evaluations for command-line coding workflows, long-horizon biology tasks, ExploitBench, and ExploitGym, indicating that it is designed to handle more than simple chat use cases. The model is priced at a lower per-token rate than Sol and Terra, making it more suitable for applications where cost efficiency is a major priority. GPT-5.6 Luna also supports the new GPT-5.6 prompt caching approach, including explicit cache breakpoints, a 30-minute minimum cache life, cache writes billed above the uncached input rate, and discounted cached-input reads. Like the rest of the GPT-5.6 family, Luna is developed with layered safeguards matched to model capability. These safeguards include trained refusals for prohibited cyber assistance, real-time misuse classifiers, paused generation for higher-risk cases, account-level review, monitoring, enforcement, automated red-teaming, and third-party human expert red-teaming. Luna is expected to support legitimate defensive and technical workflows such as code review, debugging, patch development, security education, and defensive testing while making prohibited misuse more difficult and detectable. GPT-5.6 Luna helps organizations deploy GPT-5.6-class AI where speed, affordability, scalability, and safe production use are the most important requirements.

Claude Haiku 5.5 is an Anthropic AI model built for high-volume and latency-sensitive AI workloads that require a balance of speed, cost, context capacity, and reasoning. Its primary use cases include classification, routing, information extraction, and subagent tasks within larger AI systems. Claude Haiku 5.5 introduces adaptive thinking, which allows the model to decide when reasoning is needed and how much thinking to apply before producing a response. Adaptive thinking is enabled by default, while the effort parameter gives developers a way to trade response quality against latency and cost. Developers can disable thinking at high effort or below, but Anthropic recommends using effort as the primary mechanism for controlling the model's reasoning behavior. The model provides a 1 million token context window, representing a substantial increase from the 200,000-token context window available with Claude Haiku 4.5. It can generate as many as 128,000 output tokens compared with the previous model's 64,000-token maximum, although thinking tokens are included within the configured output allowance. Browser use is available through the Claude API and Google Cloud, enabling developers to incorporate the model into workflows that require interaction with browser-based environments. Claude Haiku 5.5 uses the newer tokenizer found in Claude 4.7 and later models, resulting in approximately 30% more tokens for the same text compared with Claude Haiku 4.5, depending on the content. The model also changes several API behaviors, including replacing manual extended thinking with adaptive thinking, rejecting non-default sampling parameters and assistant-message prefills, and requiring updated computer-use tooling for supported environments.