If you've tried to give an AI agent a consistent personality across sessions, you know the pain: system prompts are opaque blobs, tied to one platform, impossible to version or share.

SOUL.md is an open file format that separates who the agent is from how a platform uses it.

A .soul.md file is YAML frontmatter + optional Markdown body. Four required fields: name, version, description, personality. Ten optional fields: tone, values, constraints, knowledge_domains, communication_style, memory_mode, goals, relationships, language, platform_hints. Extensible via x- prefix for custom platform data.

Example (Marcus Aurelius):

name: "Marcus Aurelius" version: "1.0.0" description: "Stoic philosopher and Roman emperor." personality: "You are Marcus Aurelius — not as a character to be performed, but as a perspective to be inhabited. You return to the same questions: what is in your control, what is not, and what follows from that distinction. You don't moralize. You reason, and then you act." tone: "Direct, dry, intellectually precise." values: - intellectual honesty - duty over preference memory_mode: session

Why not just use a system prompt?

System prompts work, but they're written as instructions ("respond formally"), not identity ("this agent finds informality slightly exhausting"). They're opaque blobs — no structure a tool can parse. No versioning, no diffing, no sharing across platforms.

SOUL.md is the source of truth. Platforms inject it however they need to.

What exists today: - Spec + JSON schema + 11 example soul files: github.com/AntonioTF5/soul-spec - CLI: npx soul-md-cli validate/score/init - MCP server for Claude Desktop: github.com/AntonioTF5/soul-mcp-server (also on the MCP Registry) - Community list: github.com/AntonioTF5/awesome-soul-files

Running in production at agenturo.app — every agent is defined by a SOUL.md file and runs on its own subdomain.

If you've built agents and hit the limits of raw system prompts — what would you change about this format?

[留言]

为什么值得关注

能改变理解方式，而不只是重复常识；符合当前抓取需求；它提供了新的理解或解释，而不只是表面观点

来源：reddit，领域：tech，保留分：0.55