OpenAI: GPT-5.1-Codex

GPT-5.1-Codex is a paid model from OpenAI that accepts text and image inputs and supports both tool use and reasoning. Its context window reaches 400,000 tokens, with up to 128,000 tokens available for completions, making it suitable for long documents, multi-turn workflows, and tasks that require chaining external calls. Structured output support is unconfirmed from available data, so teams with strict schema requirements should verify that capability before committing. On the comparison side, the model sits at $1.25 per million input tokens and $10.00 per million output tokens, which positions it as a mid-range option on input cost but relatively expensive on output. Its blended benchmark score of 57.2 comes from a single independent benchmark, so that figure offers limited confidence for broad capability comparisons. Buyers running output-heavy workloads should weigh that output price carefully against alternatives, while those needing large context with reasoning and tool support may find it worth shortlisting.