AI agents call fs_read_file_range to retrieve information from LocalAnt without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves file contents within a specified line range. It performs a query operation on local files without modifying, deleting, or executing anything. The 1-indexed inclusive range specification confirms it is a read-only operation. Severity is low because reading file contents poses minimal risk even if misused by an AI agent—the worst case is information disclosure of data the user already has access to.
From the tool's definition Tool name 'fs_read_file_range' and description 'Read a line range from a file' explicitly indicate data retrieval with no side effects.
Attacks that exploit this kind of access
Read a line range from a file (1-indexed, inclusive). It is categorised as a Read tool in the LocalAnt MCP Server, which means it retrieves data without modifying state.
Register the LocalAnt MCP server in PolicyLayer and add a rule for fs_read_file_range: 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 LocalAnt. Nothing to install.
fs_read_file_range 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 fs_read_file_range 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 fs_read_file_range. 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.
fs_read_file_range is provided by the LocalAnt MCP server (yuga-hashimoto/localant). 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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