Get performance metrics and health information
AI agents call getPerformanceMetrics to retrieve information from MCP Diagnostics Extension without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves performance and health diagnostic data from VS Code without creating, modifying, deleting, or executing any operations. It is a pure read operation that gathers information for observability purposes, posing minimal security risk even if misused by an AI agent.
From the tool's definition Tool name 'getPerformanceMetrics' and description 'Get performance metrics and health information' indicate data retrieval only.
Documented attack patterns abuse exactly the kind of access getPerformanceMetrics gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Diagnostics Extension, and nothing reaches the server without passing your rules. This is the rule we recommend for getPerformanceMetrics:
{
"version": "1",
"default": "deny",
"tools": {
"getPerformanceMetrics": {}
}
}getPerformanceMetrics is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get performance metrics and health information. It is categorised as a Read tool in the MCP Diagnostics Extension MCP Server, which means it retrieves data without modifying state.
Register the MCP Diagnostics Extension MCP server in PolicyLayer and add a rule for getPerformanceMetrics: 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 Diagnostics Extension. Nothing to install.
getPerformanceMetrics 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 getPerformanceMetrics 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 getPerformanceMetrics. 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.
getPerformanceMetrics is provided by the MCP Diagnostics Extension MCP server (newbpydev/mcp-diagnostics-extension). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Diagnostics Extension, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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5 MCP Diagnostics Extension tools catalogued and risk-classified — across an index of 43,000+ MCP servers.