Close the current browser instance. Returns: Status message
AI agents use close_browser to create or update resources in Mcp Browser Use — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp Browser Use environment.
An AI agent can call close_browser faster than any human can review — one bad instruction and it creates or modifies resources in Mcp Browser Use by the hundred, each call as confident as the last.
Documented attack patterns abuse exactly the kind of access close_browser gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Browser Use, and nothing reaches the server without passing your rules. This is the rule we recommend for close_browser:
{
"version": "1",
"default": "deny",
"tools": {
"close_browser": {
"limits": [
{
"counter": "close_browser_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}close_browser 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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Close the current browser instance. Returns: Status message. It is categorised as a Write tool in the Mcp Browser Use MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Mcp Browser Use MCP server in PolicyLayer and add a rule for close_browser: 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 Mcp Browser Use. Nothing to install.
close_browser 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 close_browser 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 close_browser. 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.
close_browser is provided by the Mcp Browser Use MCP server (vinayak-mehta/mcp-browser-use). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 19 Mcp Browser Use tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
19 Mcp Browser Use tools catalogued and risk-classified — across an index of 42,500+ MCP servers.