Move (cut and paste) a range of lines from one file into a different file after a given line number. The lines are removed from the source file. Use to combine or split files without manually rewriting either.
AI agents use move_lines_between_files to create or update resources in FilesystemMCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your FilesystemMCP environment.
While the tool modifies content in a way that could be undone (by moving lines back), the primary risk is that it restructures files in ways that could break application logic, corrupt data organization, or cause unintended side effects across multiple files.
From the tool's definition The tool "move_lines_between_files" performs a cut-and-paste operation: it removes lines from a source file (irreversible deletion from that location) and inserts them into a destination file.
Attacks that exploit this kind of access
Move (cut and paste) a range of lines from one file into a different file after a given line number. The lines are removed from the source file. Use to combine or split files without manually rewriting either. It is categorised as a Write tool in the FilesystemMCP 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 move_lines_between_files: 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.
move_lines_between_files 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 move_lines_between_files 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 move_lines_between_files. 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.
move_lines_between_files 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.
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