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 rules/kevin-liu-01/loop/frontend-10x-browser-debugginggit clone --depth 1 https://github.com/Kevin-Liu-01/LoopWhat 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 | $0.00436 | $0.00436 |
| Opus 5 | $0.00218 | $0.00218 |
| Sonnet 5 | $0.00087 | $0.00087 |
| Haiku 4.5 | $0.00044 | $0.00044 |
Grade A, and why
frontend-10x-browser-debugging 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.
What it actually says
Browser Debugging Preference
When browser automation or debugging is needed:
- Prefer
chrome-devtools-livewhen the user already has Chrome open, is logged in, or wants the agent to inspect the current browser state. - Prefer
chrome-devtools-portwhen testing localhost repeatedly or when a reusable dedicated debug browser is better than the user’s normal browsing session. - Use Playwright when isolation, deterministic repro, or fresh auth state is the actual goal.
- Do not default to Playwright if the user clearly wants the current browser session or selected DevTools state.
- For localhost work, favor going straight into the browser via Chrome DevTools MCP before spinning up a fresh browser automation lane.
Operational rules:
chrome-devtools-liverequires remote debugging enabled atchrome://inspect/#remote-debuggingand a user approval prompt.chrome-devtools-portassumes Chrome was launched with a remote debug port, for example via/Users/kevinliu/.codex/bin/open-chrome-debug.sh http://localhost:3000.- Playwright is fallback, not the first move, for manual browser debugging.
Cleanup rules:
MCP processes (chrome-devtools-mcp, playwright-mcp) and Playwright-managed Chrome instances accumulate across sessions and waste memory. When the user asks to clean up, shut down, or wrap up:
- Kill stale MCP processes:
pkill -f "chrome-devtools-mcp"andpkill -f "playwright-mcp" - Kill Playwright-managed Chrome:
pkill -f "ms-playwright/mcp-chrome" - Verify nothing remains:
ps aux | grep -iE "chrome-devtools-mcp|playwright-mcp|ms-playwright" | grep -v grep | wc -l - Never kill the user's normal Chrome browser or Cursor processes.
- Report what was cleaned up and confirm zero remaining.
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 · 32 lines · 436 tokens per session scan A 8eb49c507578
frontend-10x-browser-debugging is a cursor rule published in the GitHub repository Kevin-Liu-01/Loop (18 stars, last pushed 1mo ago), licensed MIT. It adds 436 tokens to every session, about $0.0022 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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