Let me break this down. The Hermes SOUL.md file is where your agent’s personality lives — the markdown file that defines who your Hermes agent is, how it talks, and how it behaves. Edit it, and you reshape your agent.
It’s one of the most underrated parts of the Hermes setup. Here’s what it is and how to use it well.
Last updated: July 2026.
Key takeaways
- SOUL.md defines your Hermes agent’s personality — identity, tone, values and behaviour.
- It lives in your agent’s workspace alongside its other config and memory files.
- Edit it in any editor — or just ask your agent (or Claude) to update it for you.
- Keep it concise: it’s loaded into context, so every line costs tokens.
- Get pre-built agent personalities in the AI Profit Boardroom Agent OS.
What Is SOUL.md in Hermes?
Hermes keeps its configuration in plain markdown files in its workspace — and SOUL.md is the one that answers “who is this agent?”. While other files handle instructions, user context and memories, SOUL.md carries the personality: the agent’s identity, tone of voice, values and general style of behaviour.
It’s read when your agent starts a session, which is why two people running the same Hermes build can have completely different-feeling agents — the soul file is doing the work.
What to Put in Your SOUL.md
- Identity — the agent’s name and role (“you are my operations agent…”)
- Tone — concise or chatty, formal or casual, emoji or none
- Priorities — what it should optimise for (speed, thoroughness, checking before acting)
- Boundaries — things it should always or never do
- Style rules — how to format answers, when to ask vs act
Think of it as the difference between hiring a contractor and briefing a long-term employee — SOUL.md is the briefing that makes the agent consistently yours.
How to Edit It
- Find your Hermes workspace folder — SOUL.md sits with the agent’s other markdown files.
- Open it in any editor and write in plain English — no code required.
- Or delegate it — ask Hermes itself (or Claude) to “update my SOUL.md so you’re more concise and always confirm before deleting anything”.
- Start a fresh session so the changes load.
- Iterate — tweak it whenever the agent’s behaviour isn’t quite right.
SOUL.md vs Memory: Personality vs Facts
A useful way to keep things clean: SOUL.md is personality, memory is facts. Who the agent is goes in the soul file; what it knows about you, your projects and your history belongs in its memory system (I use Obsidian as the second brain — see my Hermes Obsidian memory guide). Mixing the two bloats the soul file and muddies both.
Tips for a Great Soul File
- Keep it short — it’s loaded every session, so every line costs tokens. A tight half-page beats three rambling pages.
- Never put secrets in it — no API keys or credentials; that’s what proper secrets management is for.
- Be specific — “confirm before running destructive commands” beats “be careful”.
- Version it — keep a copy before big changes so you can roll back.
- One agent, one soul — with fleet profiles, give each specialist its own SOUL.md (an SEO agent shouldn’t sound like your ops agent).
Souls Across a Fleet
This gets powerful with Hermes’s fleet profiles — each profile is a fully separate agent with its own model, memory, skills and personality. A sharp, terse coding agent; a warm, careful support agent; a creative content agent — each defined by its own soul file, all routed by one gateway. See my Quicksilver update guide and agentic OS for Hermes.
Get Pre-Built Personalities
The Agent OS inside the AI Profit Boardroom ships with agent personalities already dialled in — plus the workflows, memory system and training to customise every soul file to how you work.
New here? Start free with my AI Money Lab community (free AI course + 1,000+ AI agents), or grab a free strategy session.
FAQ
What is SOUL.md in Hermes?
The markdown file that defines your Hermes agent’s personality — identity, tone, values and behaviour. It loads at session start and shapes how the agent acts.
How do I edit my Hermes SOUL.md?
Open it from your Hermes workspace in any editor and write plain English — or ask Hermes or Claude to update it for you, then start a fresh session.
What’s the difference between SOUL.md and memory?
SOUL.md is personality (who the agent is); memory is facts (what it knows about you and your work). Keep them separate for a cleaner agent.
Should SOUL.md be long?
No — it’s loaded every session, so length costs tokens. A tight, specific half-page usually beats pages of prose.
Can different agents have different souls?
Yes — with fleet profiles, each specialist agent gets its own SOUL.md, so your SEO, ops and content agents each behave (and sound) differently.
The Bottom Line
Edit SOUL.md and you reshape your agent — it’s the highest-leverage file in Hermes. The ready-made setup is in the AI Profit Boardroom.
