AI agents call websocket_get_metrics to retrieve information from Excalidraw without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool retrieves performance metrics from a WebSocket server—a read-only operation with no side effects. There is no data creation, modification, deletion, or code execution. The blast radius of misuse is minimal as metrics are informational data. This clearly falls under the Read category with low severity.
From the tool's definition Tool name 'websocket_get_metrics' and description 'Get WebSocket server performance metrics' indicate retrieval of performance data with no modification, deletion, or execution of external operations.
Documented attack patterns abuse exactly the kind of access websocket_get_metrics gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Excalidraw, and nothing reaches the server without passing your rules. This is the rule we recommend for websocket_get_metrics:
{
"version": "1",
"default": "deny",
"tools": {
"websocket_get_metrics": {}
}
}websocket_get_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 WebSocket server performance metrics. It is categorised as a Read tool in the Excalidraw MCP Server, which means it retrieves data without modifying state.
Register the Excalidraw MCP server in PolicyLayer and add a rule for websocket_get_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 Excalidraw. Nothing to install.
websocket_get_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 websocket_get_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 websocket_get_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.
websocket_get_metrics is provided by the Excalidraw MCP server (lesleslie/excalidraw-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Excalidraw, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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17 Excalidraw tools catalogued and risk-classified — across an index of 43,000+ MCP servers.