AI agents call is_dir to retrieve information from Nutstore without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool purely retrieves metadata about a file path to determine if it is a directory. It performs no side effects, creates no resources, executes no code, and makes no modifications. It is a simple read operation consistent with other query tools like 'exists' and 'get_file_info' on the same server.
From the tool's definition Tool name 'is_dir' and description '判断坚果云路径是否为目录' (Chinese: 'determine whether a Nutstore path is a directory') indicate a query operation that checks path type without modifying or executing anything.
Attacks that exploit this kind of access
判断坚果云路径是否为目录. It is categorised as a Read tool in the Nutstore MCP Server, which means it retrieves data without modifying state.
Register the Nutstore MCP server in PolicyLayer and add a rule for is_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 Nutstore. Nothing to install.
is_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 is_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 is_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.
is_dir is provided by the Nutstore MCP server (silverze/nutstore-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
Teams ship this data inside their own products. See what a licence covers →