AI agents invoke browser_tab_select to trigger actions in Playwright MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Switching browser tabs triggers navigation/browser state changes and affects which page context subsequent actions operate in. It's a browser automation action with side effects beyond mere data retrieval, fitting the Execute category. Misuse could redirect an agent's browsing context to unintended pages.
From the tool's definition Select a tab by index
Documented attack patterns abuse exactly the kind of access browser_tab_select gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Playwright MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_tab_select:
{
"version": "1",
"default": "deny",
"tools": {
"browser_tab_select": {
"limits": [
{
"counter": "browser_tab_select_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}browser_tab_select stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Select a tab by index. It is categorised as a Execute tool in the Playwright MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Playwright MCP server in PolicyLayer and add a rule for browser_tab_select: 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 Playwright MCP. Nothing to install.
browser_tab_select is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the browser_tab_select 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_select. 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_select is provided by the Playwright MCP server (korwabs/playwright-record-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Playwright MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
32 Playwright MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.