Hermes Agent plugin that pipes shell tool output through rtk for 60–90% token savings on dev operations.

Most shell tool calls a Hermes agent makes (git status, cargo test, pytest, find, …) emit far more output than the model needs. RTK is a CLI proxy that filters that noise to relevant signal. RTK already supports filter-only mode via rtk pipe -f <filter> (reads stdin, emits filtered stdout).

This plugin registers Hermes' transform_terminal_output hook and pipes raw shell output through rtk pipe whenever the command matches a known filter. Fail-open: if rtk is missing, the command isn't supported, or anything errors, the model sees the original output unchanged.

RTK's other integrations (Claude Code, Cursor, Gemini CLI, Copilot) rewrite the command — git status → rtk git status — at the PreToolUse stage. Hermes' pre_tool_call hook is currently observe-or-block only (no rewrite action), so this plugin filters on the output side instead, after the command has run. Same token savings reach the model; slight loss is filtering happens after the original command's wall-clock cost.

If/when Hermes adds a pre_tool_call rewrite action, this plugin can pivot to the args-rewrite model and gain the small efficiency back.

• Hermes Agent ≥ 0.11 (needs the transform_terminal_output hook)
• rtk on $PATH
• Python 3.10+

# Clone into the Hermes plugin directory
git clone https://github.com/ta3pks/hermes-rtk-hook.git ~/.hermes/plugins/hermes-rtk-hook

# Enable the plugin in your Hermes config
hermes plugins enable hermes-rtk-hook

# Verify it loaded
hermes plugins list | grep hermes-rtk-hook

Or symlink from a development checkout:

git clone https://github.com/ta3pks/hermes-rtk-hook.git ~/projects/hermes-rtk-hook
ln -s ~/projects/hermes-rtk-hook ~/.hermes/plugins/hermes-rtk-hook
hermes plugins enable hermes-rtk-hook

The plugin reads no config of its own. It piggybacks on rtk's existing filter set — see rtk help pipe for the canonical list. To extend coverage, add a filter to rtk upstream and a corresponding line in filter_map.py.

Currently mapped commands → rtk filters:

Anything not in this table is passed through unchanged.

git clone https://github.com/ta3pks/hermes-rtk-hook.git
cd hermes-rtk-hook
python3 -m venv .venv
.venv/bin/pip install -e '.[dev]'
.venv/bin/pytest

The test suite includes:

• Unit tests for the command → filter-name mapping (tests/test_filter_map.py)
• Hook-callback tests with mocked subprocess (tests/test_hook.py)
• Integration tests that hit the real rtk binary if it's on $PATH (tests/test_integration.py)

MIT — see LICENSE.