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On October 28, 2026, Mistral introduced the Responses API in public preview—framed for building agents on Mistral. This is a preview, not a general-availability launch. Related Responses reading: OpenAI Adds Optional 12-Hour Prompt Caching on the Responses API.
What changes versus Chat Completions
Mistral contrasts the new surface with Chat Completions: each response returns the model’s answer, reasoning, and tool calls as separate items, so applications can handle those pieces step by step. Official docs use the parallel wording function calls for the same split in the output array (messages, reasoning, and function calls)—same design, two wordings.
OpenAI Responses format—and stateless design
Docs describe building with Mistral models using the OpenAI Responses format. The same page states that this Responses API is stateless: the application keeps conversation history and resends it in each input. That fits new agent stacks or migrating an existing Responses-style integration onto Mistral’s hosted chat models. Same-day API / tooling context: GPT-6.1 Terra Is Out: Price, Work and Codex Access, and API.
Which models, and what the preview lists
Mistral says the API works with all chat models hosted by Mistral, including Large 4 (docs examples also use mistral-large-4). The stated scope is Mistral-hosted chat models.
This public preview’s docs list text I/O; image and file input; structured output (JSON mode / JSON Schema via text.format); streaming; function calling (including namespaces); reasoning (reasoning.effort and plaintext reasoning, model-dependent); and POST /v1/responses/input_tokens—for reference only.
Pricing and changelog notes
Mistral’s Responses docs page and the October 28 X announcement do not list a new Responses-specific price table or a raise/cut tied to this preview. Token pricing still follows each model’s existing rates. Mistral’s recent product reading: Mistral Launches Voxtral 3 Speech Models With Transcription From $0.0035 a Minute.
Availability, request shapes, and preview banners follow Mistral’s Responses docs and the October 28 announcement. For reference only.