Hermes

Run uvx jes login first. See Setup.

Install

uvx jes hermes-settings

Copy the hooks map it prints into ~/.hermes/config.yaml. Trust the hook when Hermes asks.

uvx jes hermes-settings

# Hermes shell hooks. Copy the hooks map into ~/.hermes/config.yaml.
# The hook command is `uvx jes@0.0.1 hermes-hook`. uvx ships with uv, so there is
# no separate jes install. Trust the hook when Hermes asks.
#
# pre_tool_call: a failed check prints action block and exits 2.
# Set fail_closed so a crashed hook does not allow the call.
# pre_llm_call: a blocked user message is injected as context.
# Hermes does not reject the user message.
# Shell hooks cannot replace a tool result or the assistant reply.

hooks:
  pre_llm_call:
    - command: uvx jes@0.0.1 hermes-hook
      timeout: 60
  pre_tool_call:
    - command: uvx jes@0.0.1 hermes-hook
      timeout: 60
      fail_closed: true

What each hook does

Event	Stage	If jes blocks
pre_llm_call	input	Prints the refusal as context and exits 2.
pre_tool_call	tool_call	Prints action: block and exits 2. The tool does not run.

fail_closed: true is set on pre_tool_call, so a hook that crashes blocks the call instead of allowing it.

Limits

• Hermes doesn't reject a blocked user message. The model sees the message and the refusal as context.
• Hermes shell hooks can't replace a tool result or the reply, so jes doesn't check those stages here. If you wire transform_tool_result or transform_llm_output to the hook anyway, they pass unchecked.