AI agents call browser_tab_list to retrieve information from Search without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns information about open browser tabs without modifying, executing, or deleting anything. It is a straightforward read operation with minimal risk—the worst case is exposing metadata about which tabs are open, which has low blast radius.
From the tool's definition Tool name 'browser_tab_list' and description 'Get the list of tabs' indicate a retrieval operation with no side effects.
Documented attack patterns abuse exactly the kind of access browser_tab_list gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Search, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_tab_list:
{
"version": "1",
"default": "deny",
"tools": {
"browser_tab_list": {}
}
}browser_tab_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get the list of tabs. It is categorised as a Read tool in the Search MCP Server, which means it retrieves data without modifying state.
Register the Search MCP server in PolicyLayer and add a rule for browser_tab_list: 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 Search. Nothing to install.
browser_tab_list is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the browser_tab_list 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_list. 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_list is provided by the Search MCP server (@agent-infra/mcp-server-search). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Search, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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36 Search tools catalogued and risk-classified — across an index of 43,000+ MCP servers.