Delete a range of lines from a file by line number. Only works within allowed directories.
AI agents call delete_lines to permanently remove resources in FilesystemMCP — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
This tool permanently removes data from files without the ability to undo the operation. Even though it operates only within allowed directories (a mitigation factor), the core function is destructive: lines deleted cannot be recovered except through external version control or backups. This is more severe than Write (reversible modifications) because the operation cannot be undone through the tool itself.
From the tool's definition Tool name 'delete_lines' combined with description 'Delete a range of lines from a file by line number' explicitly performs irreversible deletion of file content.
Attacks that exploit this kind of access
Delete a range of lines from a file by line number. Only works within allowed directories. It is categorised as a Destructive tool in the FilesystemMCP MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Filesystem MCP server in PolicyLayer and add a rule for delete_lines: 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 FilesystemMCP. Nothing to install.
delete_lines is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the delete_lines 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 delete_lines. 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.
delete_lines is provided by the Filesystem MCP server (rijadalisic/filesystemmcp). 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.
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