How to use the Mars Voice Persona agent skill (voice-persona-mars)

What is an agent skill, and what does this one do?

An agent skill is a folder containing a SKILL.md file that tells an AI agent when to use a capability and how to behave while doing it. This skill, voice-persona-mars, is version-free in this guide but is published in the gbrain repository under recipes/agent-voice/skills/voice-persona-mars. Its single file is SKILL.md.

When you talk to the voice agent and ask for depth, reflection, or an impressive demo, the agent switches to Mars. Mars has two modes. In SOLO mode it handles philosophy, presence, and patterns in your thinking. In DEMO mode it uses its tools more aggressively to show what the assistant can do, such as looking up people or companies you mention in your brain.

• SOLO mode (default): one speaker, introspective topics, "what am I thinking" framing.
• DEMO mode: multiple voices, "this is my AI" introductions, "show them what you can do" cues.
• Mars does not handle calendar, tasks, or email. It redirects those to a sister persona called Venus.

Install the voice-persona-mars skill

Download the skill ZIP from the directory page and unzip it. Then place the resulting folder in one of two locations depending on how you want to use it.

For a personal setup available across your projects, put it in ~/.claude/skills/. For a single project, put it in that project's .claude/skills/ folder.

If you use the Claude apps instead of files on disk, upload the skill under Settings → Capabilities → Skills.

• Personal install: unzip into ~/.claude/skills/
• Project install: unzip into the project's .claude/skills/ folder
• App install: Settings → Capabilities → Skills, then upload

Trigger Mars with natural requests

The skill is invoked when your voice or text input matches one of its trigger phrases. You do not need special syntax. Speak or type in a natural way that contains a trigger.

Triggers defined in the skill include "talk to mars", "ask mars", "mars,", "demo mode mars", "what's on my mind", "what am I thinking", "introspective", and "thought partner".

• "Mars, what am I actually worried about this week?"
• "What's on my mind when I think about changing jobs?"
• "Demo mode Mars, this is my AI, show them what you can do."
• "Ask Mars to help me think through why this project keeps stalling."

Start a session with Mars directly or from a topic

The voice agent picks the persona from a session setting. You can open a WebRTC session with ?persona=mars on the /session endpoint, or set DEFAULT_PERSONA=mars if Mars should be your default.

To call Mars from inside a specific conversation topic, add a topicId (lowercase letters, numbers, and hyphens only) and an optional topicName. Mars then starts already knowing that topic's recent conversation. Only the topicId is sent; the server looks up the context itself, so do not put topic content in the URL.

Know what Mars can and cannot do

Mars uses tools sparingly in solo mode: search, get_page, and read_article. In demo mode it searches the brain more often and summarises links with read_article. The skill states that a general web-search tool is not in the shipped allow-list and must be wired host-side if you want one.

The voice agent runs with a read-only tool allow-list, so Mars cannot write to your brain unless you opt in through a local override. If you ask it to save something, it will say it cannot save from voice.

• Calendar, tasks, and email tools exist in the read-only list but are deliberately not used by Mars.
• Mars is English-only in this release and will say so if you speak another language.
• Output is spoken audio over WebRTC, not a text file written to your brain.

Safety notes: scripts and network access

The skill file itself does not run scripts. It does use the network, because it depends on a live voice session over WebRTC and on the voice agent service. The shipped prompt is described as containing no personal names or private filesystem paths, and the repository includes checks for that.

The persona prompt file and the voice agent service are referenced by the skill but were not included in the files reviewed for this listing, so their behaviour cannot be confirmed from the skill alone.

• Runs scripts: no
• Uses network: yes
• Writes to the brain: no, unless you opt in locally

Tips for a good session

Mars works best when you bring a real question about meaning, patterns, or something you are weighing. Surface-level scheduling will be handed to Venus, so keep logistics for that persona.

If you want Mars to draw on your notes, make sure your brain directory is populated before you start. Topic-based calls and search depend on it.

• Give Mars a specific topic or a feeling you want to examine.
• Ask it to look up a named person or concept from your notes to ground the conversation.
• Use demo mode only when an audience is present and you want the showcase behaviour.