AI agents call health_check to retrieve information from Open Stocks MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves status information about the MCP server itself with no side effects, no data modification, and no external operations triggered. It is a diagnostic query operation typical of health monitoring endpoints, making it a straightforward Read category tool with low severity.
From the tool's definition Tool name 'health_check' and description 'Gets health status of the MCP server' indicate a read-only operation that queries server status without modifying or executing operations.
Documented attack patterns abuse exactly the kind of access health_check gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Open Stocks MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for health_check:
{
"version": "1",
"default": "deny",
"tools": {
"health_check": {}
}
}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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Gets health status of the MCP server. It is categorised as a Read tool in the Open Stocks MCP MCP Server, which means it retrieves data without modifying state.
Register the Open Stocks MCP server in PolicyLayer and add a rule for 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 Open Stocks MCP. Nothing to install.
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 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 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.
health_check is provided by the Open Stocks MCP server (open-agent-tools/open-stocks-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Open Stocks 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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152 Open Stocks MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.