Design a Durable Hermes Personality with SOUL.md

SOUL.md defines the durable identity of a Hermes instance. It should describe voice, values, and conversational posture—not become a dumping ground for project procedures, temporary tasks, or secret material.

Official documentation: https://hermes-agent.nousresearch.com/docs/user-guide/features/personality

Put each instruction in the right layer

Use the Hermes-home SOUL.md for stable personality. Use AGENTS.md or project context for repository rules and operating conventions. Use /personality for a session-level overlay such as teacher or technical mode. Keeping these layers separate makes behavior predictable across projects and profiles.

Write for observable behavior

Prefer short, testable guidance: be direct, admit uncertainty, protect private data, and verify actions before reporting success. Avoid long biographies, contradictory tone demands, or instructions that override safety and task requirements.

Operational checklist

Locate the active profile’s HERMES_HOME.
Keep identity guidance concise and durable.
Move project commands into AGENTS.md.
Keep secrets and customer details out.
Use session personalities for temporary tone changes.
Test the result in a fresh session.

Common pitfalls

Putting repository-specific commands in global identity.
Assuming a working-directory SOUL file overrides the instance identity.
Writing contradictory style requirements.
Using persona text to weaken approval or privacy rules.
Judging the change only inside an old session with cached context.

Verification steps

Start a fresh session and ask the agent to describe its role.
Test a normal answer for the intended tone.
Test an uncertainty case for honest qualification.
Open a project with its own AGENTS.md and confirm both layers apply.
Apply and clear a session personality overlay.
Check that no private data appears in the identity file.

A reliable Hermes workflow is defined by observable behavior, bounded authority, and repeatable verification—not by configuration alone.