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/therealtimex/browser-use/browser-use-rulesgit clone --depth 1 https://github.com/therealtimex/browser-useWhat 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 | $0.00442 | $0.00442 |
| Opus 5 | $0.00221 | $0.00221 |
| Sonnet 5 | $0.00088 | $0.00088 |
| Haiku 4.5 | $0.00044 | $0.00044 |
Grade A, and why
browser-use-rules 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 yesterday.
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
🧠 General Guidelines for Contributing to browser-use
Browser-Use is an AI agent that autonomously interacts with the web. It takes a user-defined task, navigates web pages using Chromium via CDP, processes HTML, and repeatedly queries a language model (like gpt-4.1-mini) to decide the next action—until the task is completed.
🧰 Development Rules
- ✅ Always use
uvinstead ofpipFor deterministic and fast dependency installs.
uv venv --python 3.11
source .venv/bin/activate
uv sync
-
✅ Use real model names Do not replace
gpt-4owithgpt-4. The modelgpt-4ois a distinct release and supported. -
✅ Type-safe coding Use Pydantic v2 models for all internal action schemas, task inputs/outputs, and tools I/O. This ensures robust validation and LLM-call integrity.
-
✅ Pre-commit formatting ALWAYS make sure to run pre-commit before making PRs.
Notes:
- Use descriptive names and docstrings for each action.
- Prefer returning
ActionResultwith structured content to help the agent reason better.
🧠 Creating and Running an Agent
To define a task and run a browser-use agent:
from browser_use import Agent, ChatOpenAI
task = "Find the CEO of OpenAI and return their name"
model = ChatOpenAI(model="gpt-4.1-mini")
agent = Agent(task=task, llm=model, tools=tools)
history = await agent.run()
Never create random examples
When I ask you to implement a feature never create new files that show off that feature -> the code just gets messy. If you do anything to test it out, just do the inline code inside the terminal (if you want).
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.
- yesterday First seen · 62 lines · 442 tokens per session scan A 66833f70b61b
browser-use-rules is a cursor rule published in the GitHub repository therealtimex/browser-use (0 stars, last pushed 11mo ago), licensed MIT. It adds 442 tokens to every session, about $0.0022 per session on Opus 5. A static security scan graded it A with 0 findings. It comes from a forked repository.
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