# Mistral Medium 3.5 — 128B Open-Weight Flagship Hits 77.6% on SWE-Bench Verified

> Mistral's new flagship: 128B dense, 256k context, open weights under modified MIT, and a 77.6 SWE-Bench Verified score.

- Org: Mistral AI
- Date: 2026-04-29
- Category: model, tool
- Source: https://mistral.ai/news/vibe-remote-agents-mistral-medium-3-5
- Canonical page: https://ai-tldr.dev/releases/mistral-medium-3-5/

## In short

Mistral Medium 3.5 — 128B dense open-weight model, 256k context, 77.6% on SWE-Bench Verified and 91.4 on τ³-Telecom. Ships with Vibe Remote Agents (async cloud coding agents) and Le Chat Work mode. $1.5/$7.5 per MTok via API.

## What it is

Mistral Medium 3.5 is the newest dense flagship model from Mistral AI, released April 29 with open weights on Hugging Face under a modified MIT license. The same launch ships Vibe Remote Agents — async coding agents that run in cloud sandboxes — and a new Work mode for Le Chat. Mistral Medium 3.5 becomes the default model in both Le Chat and the Vibe CLI.

## How it works

The model is 128B dense parameters with a 256k-token context window, trained for instruction-following, reasoning, and coding. Vibe Remote Agents launch from the Vibe CLI or Le Chat into isolated cloud sandboxes, run in parallel, and integrate with GitHub, Linear, Jira, Sentry, Slack, and Teams. A local Vibe session can be 'teleported' to the cloud mid-task. API pricing is $1.5 per million input tokens and $7.5 per million output tokens.

## Why it matters

The 77.6% SWE-Bench Verified score puts an open-weight 128B dense model into the same coding-tier conversation as much larger closed flagships. Combined with remote agent infrastructure, Mistral now ships an end-to-end coding-agent stack — model, CLI, cloud orchestration — under permissive open weights. Teams that want a self-hostable alternative to Claude/Codex with first-party agent tooling now have one.

## Who it's for

Teams running self-hosted coding agents and developers wanting open-weight SWE-Bench-tier models

## Try it

huggingface.co/mistralai/Mistral-Medium-3.5-128B

## Links

- [Announcement](https://mistral.ai/news/vibe-remote-agents-mistral-medium-3-5)
- [HuggingFace](https://huggingface.co/mistralai/Mistral-Medium-3.5-128B)
- [Docs](https://docs.mistral.ai/)