AI agents use copy_items to create or update resources in Filesystem — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Filesystem environment.
Copying files/directories creates or modifies the filesystem state by introducing new files, but the operation is reversible (copies can be deleted). This fits the Write category definition: 'creates or modifies data reversibly.' The severity is medium because uncontrolled copying could fill disk space or duplicate sensitive files, but the risk is less severe than destructive or financial operations.
From the tool's definition Tool description states 'Copy multiple specified files/directories' — this creates new data by duplicating existing files/directories, which is a reversible write operation.
Documented attack patterns abuse exactly the kind of access copy_items gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Filesystem, and nothing reaches the server without passing your rules. This is the rule we recommend for copy_items:
{
"version": "1",
"default": "deny",
"tools": {
"copy_items": {
"limits": [
{
"counter": "copy_items_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}copy_items stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Copy multiple specified files/directories. It is categorised as a Write tool in the Filesystem MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Filesystem MCP server in PolicyLayer and add a rule for copy_items: 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 Filesystem. Nothing to install.
copy_items is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the copy_items 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 copy_items. 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.
copy_items is provided by the Filesystem MCP server (sylphxai/filesystem-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Filesystem, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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13 Filesystem tools catalogued and risk-classified — across an index of 43,000+ MCP servers.