🔥 PREFERRED METHOD: Activate (focus) a specific tab in Google Chrome using its unique tab ID. Brings the tab to the front and makes it active. Extract the Tab ID from [Tab ID: 1234567890] in get_tabs output.
AI agents invoke activate_tab_by_id to trigger actions in MCP Browser Tabs Server. 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.
This tool triggers an external browser operation (focusing/activating a tab) via AppleScript, which constitutes executing an action in an external application. It doesn't merely read data, nor does it destructively delete anything, but it does control browser state by switching the active tab, which falls under Execute as it triggers an external operation whose effect depends on the tab ID argument.
From the tool's definition Activate (focus) a specific tab in Google Chrome... Brings the tab to the front and makes it active
Documented attack patterns abuse exactly the kind of access activate_tab_by_id gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Browser Tabs Server, and nothing reaches the server without passing your rules. This is the rule we recommend for activate_tab_by_id:
{
"version": "1",
"default": "deny",
"tools": {
"activate_tab_by_id": {
"limits": [
{
"counter": "activate_tab_by_id_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}activate_tab_by_id 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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🔥 PREFERRED METHOD: Activate (focus) a specific tab in Google Chrome using its unique tab ID. Brings the tab to the front and makes it active. Extract the Tab ID from [Tab ID: 1234567890] in get_tabs output. It is categorised as a Execute tool in the MCP Browser Tabs Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the MCP Browser Tabs Server MCP server in PolicyLayer and add a rule for activate_tab_by_id: 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 Tabs Server. Nothing to install.
activate_tab_by_id 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 activate_tab_by_id 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 activate_tab_by_id. 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.
activate_tab_by_id is provided by the MCP Browser Tabs Server MCP server (kazuph/mcp-browser-tabs). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Browser Tabs Server, 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.
4 MCP Browser Tabs Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.