Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/vre/flow-state/firefox-controlnpx skills add vre/flow-state --skill firefox-controlgit clone --depth 1 https://github.com/vre/flow-stateWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00037 | $0.00629 |
| Opus 5 | $0.00018 | $0.00315 |
| Sonnet 5 | $0.00007 | $0.00126 |
| Haiku 4.5 | $0.00004 | $0.00063 |
Grade A, and why
firefox-control scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Firefox Control
Control Firefox via WebDriver BiDi. Connects to Firefox launched with
--remote-debugging-port. No geckodriver needed — direct BiDi WebSocket.
TEST TOOL: Firefox sets navigator.webdriver=true on any remote debugging
session. Every anti-bot system detects this. Mozilla has no extension-based
automation API and no runtime toggle. For production agent workflows, use
Chrome CDP tooling instead.
Prerequisites
User must launch Firefox with: firefox --remote-debugging-port 9223
The daemon starts automatically on first command. No explicit start needed.
The daemon holds the BiDi WebSocket open so each CLI call is instant — no connection overhead. Each command is a one-shot call; the caller does not hold any connection. The daemon idles out after 5 min of no commands. Unix socket: /tmp/firefoxctl-{uid}.sock.
Tool responses are sanitized: prompt-injection markers in page content are stripped before reaching the LLM.
Commands
firefoxctl.py list
firefoxctl.py open https://example.com
firefoxctl.py status
firefoxctl.py targets
firefoxctl.py stop
Use --json for machine-parseable JSON output (default is human-readable).
Target commands
All target commands: firefoxctl.py CONTEXT COMMAND [ARGS]
Context ID from list output (full UUID required — no prefix match).
firefoxctl.py CONTEXT eval "document.title"
firefoxctl.py CONTEXT screenshot -o page.png
firefoxctl.py CONTEXT console-tail --for 30
firefoxctl.py CONTEXT navigate https://example.com
DOM helpers
Shorthands for common eval patterns. Selectors are CSS.
click/check/uncheck/highlight SELECTOR
submit/clear FORM
type/fill SELECTOR TEXT
select SELECTOR VALUE
get-text/get-html/get-value/exists/count/get-texts SELECTOR
get-attr SELECTOR ATTR
scroll-to/wait-for/wait-hidden SELECTOR
wait-text SELECTOR TEXT
navigate URL
wait-url PATTERN
scroll-up/scroll-down [PIXELS]
scroll-by X Y
inject-css CSS
reload/back/forward/get-title/get-url/scroll-top/scroll-bottom
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 84 lines · 37 tokens per session scan A f9e49487ca3f
firefox-control is a skill published in the GitHub repository vre/flow-state (12 stars, last pushed 2mo ago), licensed MIT. It adds 37 tokens to every session and 629 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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