Get page performance metrics from Performance API.
AI agents call get_performance_metrics to retrieve information from JS Reverse Strong MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries performance data from the browser's Performance API, which is a passive observation capability. It retrieves metrics (timing, navigation, resource durations, etc.) without triggering code execution, modifying state, or causing side effects. This is a classic Read operation: it gathers information for analysis in the context of reverse engineering workflows without altering the target environment.
From the tool's definition Tool description states it 'Get[s] page performance metrics from Performance API' — a retrieval operation with no modification, execution, or deletion of data. The Performance API provides read-only access to browser timing and performance data.
Documented attack patterns abuse exactly the kind of access get_performance_metrics gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and JS Reverse Strong MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for get_performance_metrics:
{
"version": "1",
"default": "deny",
"tools": {
"get_performance_metrics": {}
}
}get_performance_metrics is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get page performance metrics from Performance API. It is categorised as a Read tool in the JS Reverse Strong MCP MCP Server, which means it retrieves data without modifying state.
Register the JS Reverse Strong 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 JS Reverse Strong MCP. 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 JS Reverse Strong MCP server (lwjjike/jsreverser-strong-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from JS Reverse Strong MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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85 JS Reverse Strong MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.