AI agents call get_performance_metrics to retrieve information from Selenium without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves performance metrics from a browser page, which is a read-only query operation. It does not execute arbitrary code, modify state, delete data, or initiate external operations. The data returned (timing information) is passive monitoring information.
From the tool's definition Tool name is 'get_performance_metrics' and description states 'Return page performance timing data.' The verb 'Return' and 'get' prefix indicate data retrieval with no modification or side effects.
Attacks that exploit this kind of access
Return page performance timing data. It is categorised as a Read tool in the Selenium MCP Server, which means it retrieves data without modifying state.
Register the Selenium MCP server in PolicyLayer and add a rule for get_performance_metrics: 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 Selenium. Nothing to install.
get_performance_metrics 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 get_performance_metrics 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 get_performance_metrics. 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.
get_performance_metrics is provided by the Selenium MCP server (scv-consultants/selenium-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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