AI agents call list_dir to retrieve information from McpVanguard without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only queries the filesystem to enumerate contents—it has no side effects, cannot modify data, execute code, or cause destructive operations. The virtual filesystem context suggests it is further constrained. Classification as Read with low severity is appropriate, as directory enumeration presents minimal risk even if misused by an AI agent.
From the tool's definition The tool name 'list_dir' and description 'List contents of a directory in the virtual filesystem' indicate a read-only operation that retrieves directory metadata without modifying, deleting, or executing any code.
Documented attack patterns abuse exactly the kind of access list_dir gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and McpVanguard, and nothing reaches the server without passing your rules. This is the rule we recommend for list_dir:
{
"version": "1",
"default": "deny",
"tools": {
"list_dir": {}
}
}list_dir is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List contents of a directory in the virtual filesystem. It is categorised as a Read tool in the McpVanguard MCP Server, which means it retrieves data without modifying state.
Register the McpVanguard MCP server in PolicyLayer and add a rule for list_dir: 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 McpVanguard. Nothing to install.
list_dir 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 list_dir 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 list_dir. 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.
list_dir is provided by the McpVanguard MCP server (provnai/mcpvanguard). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from McpVanguard, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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4 McpVanguard tools catalogued and risk-classified — across an index of 43,000+ MCP servers.