How to build a Reddit research agent using Mistral Vibe skills

Picture this: you've got fifteen Reddit tabs open across r/wallstreetbets, r/cryptocurrency, and a handful of niche subreddits, and you need a sentiment read — long, flat, or short — before the market moves. Doing that manually means scrolling, copy-pasting, and losing five minutes you don't have. Now imagine pressing a keyboard shortcut, saying a sentence out loud, and getting a structured summary back in under 30 seconds. That's not a hypothetical. It's exactly what a custom-built research skill inside Mistral Vibe can do.

This guide walks through how to build that kind of agent yourself — using Vibe's browser automation, voice input, and reusable Skills system to turn scattered Reddit scrolling into a repeatable, fast research workflow.

What is Mistral Vibe, exactly?

Mistral Vibe is Mistral's unified AI chat and agent product, combining what used to be Le Chat with a dedicated coding agent. Vibe is Mistral's AI chat assistant and agent for work and code, combining an AI chat assistant and an AI coding agent in a single product for individuals, teams, and enterprises. That matters for a Reddit research agent because you're not just chatting with a model — you're building something that can take actions: browsing tabs, running commands, and executing a repeatable skill on demand.

On the voice side, Vibe supports voice input powered by Voxtral, which is what makes the "press a shortcut and just talk" workflow possible instead of typing out a prompt every time.

Why build a custom skill instead of just prompting?

Typing the same detailed instructions into a chat window every single time you want a sentiment check is slow and error-prone. Vibe solves this with a Skills system, and it's worth understanding before you build anything.

Skills are reusable instruction sets that extend Vibe Code with new workflows, custom slash commands, and scoped tool sets, and Vibe follows the Agent Skills specification, so skills you write are portable to other agents that adopt the same spec. In plain terms: you write the workflow once — "scroll these subreddits, grab the top posts and comment sentiment, summarize as long/flat/short" — and then trigger it instantly with a slash command or voice phrase from then on.

The official Skills documentation is the best starting point, and the structure is simple. A skill is a directory containing a SKILL.md file, and the file starts with YAML frontmatter and continues with the skill instructions in Markdown. A minimal skill definition looks like this in practice — name, description, and which tools it's allowed to touch, followed by the actual instructions the agent follows.

How do you set up Mistral Vibe for the first time?

Before building the Reddit skill, you need Vibe installed and configured. Here's the fast path:

1. Head to the Mistral Vibe product page and sign up for an account.
2. Grab an API key. As the PyPI package page explains, to use Vibe, you'll need a Mistral API key, which you can obtain by signing up at console.mistral.ai.
3. Install the CLI. For first-timers, when you run Vibe for the first time or if your API key is missing, Vibe will prompt you to enter it, and the key will be securely saved to ~/.vibe/.env for future sessions.
4. Check out the GitHub repository for the full open-source CLI code and setup instructions if you want to inspect or modify how it works.

Once installed, Vibe automatically pulls in context about your environment. Vibe automatically scans your project's file structure and Git status to provide relevant context to the agent, improving its understanding of your codebase. That same context-awareness extends to browser tabs when you're using it for research rather than pure coding tasks.

How do you turn browser tabs into research context?

This is where the Reddit agent idea gets interesting. Vibe isn't limited to reading files — it can be pointed at open browser tabs to pull live context. The workflow looks like this in practice: open your Reddit tabs (subreddit feeds, individual threads, comment sections), then let a browsing-capable agent scroll through each one, extracting post titles, upvote patterns, and comment sentiment as it goes.

The key here is scoping the skill's tools correctly. Pair custom skills with allowed-tools to keep their access scoped to what the workflow needs. For a research skill, that typically means read-only access — no file writes, no destructive commands — just browsing, reading, and summarizing.

How do you actually write the Reddit sentiment skill?

Start with the SKILL.md template. Based on the format Mistral documents, your file structure would look something like this conceptually:

name: reddit-sentiment
description: Scrape open Reddit tabs and summarize sentiment as long, flat, or short for a given ticker or topic
license: MIT
user-invocable: true
allowed-tools:
  - browser_read
  - grep
  - ask_user_question

Below the frontmatter, the markdown body contains the actual instructions: which subreddits to prioritize, how many posts to sample, what counts as bullish vs. bearish language, and the exact output format you want (a short sentiment tag plus supporting evidence, not a wall of text).

Two settings matter a lot for making this skill usable day-to-day:

• user-invocable: true — this is what makes the skill available as a slash command. Skills are the recommended way to add your own slash commands, and setting user-invocable: true in the frontmatter makes the skill name available with /skill-name autocompletion in the CLI prompt and in the VS Code extension slash picker too.
• Where you save it — project-specific skills should live in a dedicated folder so teammates can review them, while personal ones go in your home directory. Project-level skills go in ./.vibe/skills/ or ./.agents/skills/ when the working directory is trusted, and user-level skills go in ~/.vibe/skills/.

Can you trigger the agent with voice instead of typing?

Yes, and this is arguably the biggest speed unlock for a live research workflow. Instead of typing "/reddit-sentiment" and a paragraph of context every time, you record a voice command, Vibe transcribes it via Voxtral, and the skill fires with your spoken instructions as the prompt. That means when you're mid-trading-session and need a fast read on WSB chatter, you don't break flow to type — you talk, and the agent does the rest while you keep watching your charts.

What about permissions and safety?

Letting an agent browse and summarize is low-risk, but it's worth locking down tool access anyway, especially as you experiment. Review a skill before enabling it if it can call write-capable tools, and prefer narrow allowed-tools lists over disabling tools elsewhere. For a research-only skill, there's no reason to grant write, delete, or shell-execution permissions at all — keep it read-and-summarize only.

If you want more granular control, Vibe's agent profile system lets you build a dedicated, restricted agent just for this purpose rather than relying on the default profile. You can create custom agents in ~/.vibe/agents/ at the user level or ./.vibe/agents/ at the project level by adding a .toml file, and every agent must declare its kind via agent_type. A read-only "research" subagent, similar to the pattern Mistral documents, keeps the whole thing safely sandboxed.

Where do you find more pre-built skills to speed this up?

You don't have to build every skill from scratch. AgentSkill.sh maintains a large public directory of Vibe-compatible skills covering research, debugging, and content workflows, and it includes skills that provide a systematic methodology for thorough web research and generate professional consulting-grade research reports with structured analysis frameworks. These are a great starting point to fork and adapt into your own Reddit-specific version instead of writing the whole SKILL.md cold.

What should you actually measure to know it's working?

Speed is the whole point of this build, so track it. Time how long a manual scroll-and-summarize session takes versus the skill-triggered version. If the skill isn't meaningfully faster — say, under 30 seconds from voice command to structured summary — go back and trim the instructions in your SKILL.md. Long, rambling skill descriptions burn tokens and slow down execution; tight, specific instructions with a clear output format are what make these agents fast in practice.

Reddit sentiment moves markets faster than most people can read a thread. Build the agent once, tune it until it's fast, and you'll never have to manually scroll WSB at 2am again.