AI agents call directory_tree to retrieve information from MCP Filesystem Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
A directory tree operation retrieves and displays filesystem hierarchy information without creating, modifying, or deleting any data. This is a read-only query operation with minimal risk. Low severity because disclosure of directory structure alone has limited impact unless sensitive paths are exposed, which depends on implementation and access controls.
From the tool's definition Tool name 'directory_tree' and sibling tools like 'calculate_directory_size', 'get_file_info', 'compare_files', 'find_duplicate_files', 'grep_files' are all read-only filesystem operations.
Documented attack patterns abuse exactly the kind of access directory_tree gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Filesystem Server, and nothing reaches the server without passing your rules. This is the rule we recommend for directory_tree:
{
"version": "1",
"default": "deny",
"tools": {
"directory_tree": {}
}
}directory_tree is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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directory_tree. It is categorised as a Read tool in the MCP Filesystem Server MCP Server, which means it retrieves data without modifying state.
Register the MCP Filesystem Server MCP server in PolicyLayer and add a rule for directory_tree: 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 Filesystem Server. Nothing to install.
directory_tree 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 directory_tree 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 directory_tree. 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.
directory_tree is provided by the MCP Filesystem Server MCP server (safurrier/mcp-filesystem). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 21 MCP Filesystem Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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21 MCP Filesystem Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.