Mistral's Vibe CLI, the open-source terminal coding assistant launched alongside Devstral 2 in early December, now supports configurations that let developers build reusable instruction sets for different tasks. The feature, documented in Mistral's configuration guide, allows custom agent profiles stored in ~/.vibe/agents/ that can override default behavior for specialized workflows.
Think of it as creating personas for specific jobs. A security audit agent might disable file-write permissions while keeping bash access open. A code review agent could use a different system prompt entirely. Developers switch between them with --agent my_custom_agent at launch.
The configuration system also makes model switching trivial. While Vibe defaults to Devstral 2 (72.2% on SWE-bench Verified), users can point it at Magistral, Mistral's reasoning-focused model, through a simple config.toml edit. One network engineer documented using exactly this setup, falling back to Magistral when Devstral gets stuck on complex infrastructure tasks. The strategy: use Devstral until it seems to get stumped, then switch to Magistral, which handles reasoning-heavy problems better.
Custom system prompts live in ~/.vibe/prompts/ as markdown files. Reference them by filename (minus the .md extension) in your config, and Vibe loads your instructions instead of the default coding-assistant prompt. The whole system supports glob patterns and regex for enabling or disabling specific tools.
The Bottom Line: Vibe CLI's configuration layer turns a general-purpose coding agent into a customizable toolkit, with the model-switching feature making it practical to use specialized models without leaving your terminal.
QUICK FACTS
- Custom agents stored in
~/.vibe/agents/as TOML files - System prompts configurable via
~/.vibe/prompts/directory - Model switching supported for Devstral, Magistral, and third-party providers
- Devstral 2 API access remains free through December 2025 (Mistral-reported)
- Vibe CLI released December 9, 2025 under Apache 2.0 license
