AI agents use browser_tab_close to create or update resources in Fast Playwright MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Fast Playwright MCP environment.
An AI agent can call browser_tab_close faster than any human can review — one bad instruction and it creates or modifies resources in Fast Playwright MCP by the hundred, each call as confident as the last.
Documented attack patterns abuse exactly the kind of access browser_tab_close gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Fast Playwright MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_tab_close:
{
"version": "1",
"default": "deny",
"tools": {
"browser_tab_close": {
"limits": [
{
"counter": "browser_tab_close_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}browser_tab_close 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 a tab by index or close current tab. It is categorised as a Write tool in the Fast Playwright MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Fast Playwright MCP server in PolicyLayer and add a rule for browser_tab_close: 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 Fast Playwright MCP. Nothing to install.
browser_tab_close 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_tab_close 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_tab_close. 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_tab_close is provided by the Fast Playwright MCP server (tontoko/fast-playwright-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 34 Fast Playwright MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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34 Fast Playwright MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.