hermes-tabs plugin

Settings page and guard rails for hermes-tabs, which lets Hermes work in individual tabs of your real, signed-in Chromium browser (Chrome, Vivaldi, Edge, Brave) through an extension and a small MCP relay.

This plugin alone does nothing. It needs the hermes-tabs relay and browser extension from the main repository, and the relay registered in Hermes as the MCP server tabs. Setup: see the main README.

What it adds

• Settings → Plugins → "Hermes in the Browser" (desktop half, opt-in): which browser Hermes works in (when several are connected to the relay: show each one's settings, pick the one for Hermes), master switch, safety (level read / standard / extended / full and the single switches, see Safeguards), default for all websites (ask or allow all), temporary "allow all", allowed and blocked sites. The values live in the browser extension and are enforced there.
• Tightening applies at once, loosening needs the browser. Every change that loosens something (a more permissive level, switching an ability or relaxation on, "allow all websites", switching the master switch on, removing a blocked site) must be confirmed by you in the browser. The page then shows "Please confirm in the browser …" (the relay waits up to 120 s) and afterwards the result. While Hermes may enter passwords, a red warning is shown. The safety section needs extension 0.9.0 or later; with an older extension it only says so.
• Language: the settings page follows the language set in Hermes (and switches live): English, German, French, Spanish, Russian, Japanese, Chinese (simplified and traditional) and Arabic, as in the Hermes desktop app; other languages fall back to English. The German and English texts are maintained by hand, all others are machine translations - corrections are welcome (the texts are the STR object in desktop/plugin.js).
• pre_tool_call hook:
  • master switch off: mcp__tabs__* calls are rejected early;
  • hosts listed in HERMES_TABS_OWN_HOSTS (the agent's own interface) are never operated through the extension, so the agent cannot grant itself permissions through the browser;
  • opt-in, off by default (switch "Also block for Hermes' other web tools", stored in plugin-data/hermes-tabs/options.json): blocked sites and own hosts also apply to Hermes' own browser tools (browser_exec, browser_cdp) and web_extract when the domain appears in the arguments.

Configuration

Variable	Purpose
HERMES_TABS_ADMIN_TOKEN	required; admin token of the relay (read through Hermes' secret scope)
HERMES_TABS_RELAY	relay URL, default http://127.0.0.1:8766
HERMES_TABS_OWN_HOSTS	comma-separated hosts of the agent's own interface, default empty

Disclosure

• Network: HTTP requests only to the hermes-tabs relay you configure (HERMES_TABS_RELAY, default localhost), paths /admin/settings (a change that loosens something waits there for your confirmation, up to 140 s on the plugin's side; the desktop page passes the same timeout to Hermes, whose default of 15 s would cut it off) and /admin/select, authenticated with HERMES_TABS_ADMIN_TOKEN. No third-party services, no telemetry.
• Files: caches the last seen settings in <HERMES_HOME>/plugin-data/hermes-tabs/settings.json, of the browser Hermes works in, so the hook keeps working while the browser is closed. No other reads outside the plugin's own data.
• No shell commands, background processes, self-updates or stored credentials.

License: MIT