Mistral Medium 3.5

Mistral Medium 3.5 is a 128-billion-parameter dense language model developed by Mistral AI, publicly available under a modified MIT open-weights license. Designed as a flagship merged model, it handles instruction-following, reasoning, and coding tasks through a single set of weights, with a 256,000-token context window. The model also includes a vision encoder trained from scratch to process variable image sizes and aspect ratios. It is optimized for agentic workflows, long-horizon tasks, and structured output generation, achieving notable scores such as 77.6% on SWE-Bench Verified and 91.4 on τ³-Telecom. Mistral Medium 3.5 is deployable on as few as four GPUs for self-hosted use, and its reasoning effort can be configured per request, allowing it to switch between quick responses and complex multi-step operations.

This model serves as the default engine for two major Mistral AI products: Le Chat and Mistral Vibe. In Le Chat, Mistral Medium 3.5 powers a new 'Work mode' that enables multi-step tasks such as research, analysis, and cross-tool actions by calling tools in parallel until completion. In Mistral Vibe, it supports remote asynchronous coding agents that run in the cloud, can be spawned from the command-line interface or directly from Le Chat, and continue working while users step away. These agents are designed for async coding sessions that offload tasks without interrupting conversations.

As part of Mistral AI's broader ecosystem, Mistral Medium 3.5 represents a convergence of coding, reasoning, and instruction-following capabilities into a single compact model. Its open-weights release allows developers to self-host and fine-tune the model, while hosted access is available through Mistral's platform. The platform itself includes additional features such as text and image input processing, though current capabilities are focused on text and image modalities. Pricing for hosted services and free-tier limits are not explicitly detailed in the available scraped content and should be verified on the official website.