Save cookies for current domain as a named auth session.
AI agents use browser_auth_save to create or update resources in Termux Browser Pilot — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Termux Browser Pilot environment.
This tool creates/writes new authentication session data (cookies) to persistent storage, making it a Write operation. The severity is high because compromised auth sessions could enable unauthorized access to sensitive user accounts and services if an AI agent misuses this capability to save malicious or attacker-controlled cookies.
From the tool's definition The tool description explicitly states 'Save cookies for current domain as a named auth session.' This creates and stores new authentication data.
Documented attack patterns abuse exactly the kind of access browser_auth_save gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Termux Browser Pilot, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_auth_save:
{
"version": "1",
"default": "deny",
"tools": {
"browser_auth_save": {
"limits": [
{
"counter": "browser_auth_save_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}browser_auth_save stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Save cookies for current domain as a named auth session. It is categorised as a Write tool in the Termux Browser Pilot MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Termux Browser Pilot MCP server in PolicyLayer and add a rule for browser_auth_save: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Termux Browser Pilot. Nothing to install.
browser_auth_save is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the browser_auth_save rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for browser_auth_save. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
browser_auth_save is provided by the Termux Browser Pilot MCP server (salviz/termux-browser-pilot). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Termux Browser Pilot, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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148 Termux Browser Pilot tools catalogued and risk-classified — across an index of 43,000+ MCP servers.