AI agents call websocket_health_check 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.
This tool performs a read-only health check of the WebSocket server. It queries and retrieves status information but performs no modifications, creations, deletions, or external operations. The blast radius of misuse is minimal—an agent could spam health checks but cannot alter diagrams, execute code, or cause side effects. This clearly falls under the Read category.
From the tool's definition Tool name 'websocket_health_check' and description 'Check WebSocket server health and status' indicate a diagnostic query operation that retrieves status information without modifying state.
Documented attack patterns abuse exactly the kind of access websocket_health_check 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_health_check:
{
"version": "1",
"default": "deny",
"tools": {
"websocket_health_check": {}
}
}websocket_health_check is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Check WebSocket server health and status. 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_health_check: 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_health_check 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_health_check 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_health_check. 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_health_check 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.