List files in a directory
AI agents call listFiles to retrieve information from Expo MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Listing files is a read-only operation with no side effects. It retrieves information about the filesystem structure but does not create, modify, delete, or execute anything. The blast radius if misused is minimal — an AI agent could only discover what files exist, which is typically low-sensitivity in development contexts.
From the tool's definition Tool name is 'listFiles' and description states 'List files in a directory' — this is a query operation that retrieves directory contents without modifying or executing anything.
Attacks that exploit this kind of access
List files in a directory. It is categorised as a Read tool in the Expo MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Expo MCP Server MCP server in PolicyLayer and add a rule for listFiles: 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 Expo MCP Server. Nothing to install.
listFiles 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 listFiles 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 listFiles. 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.
listFiles is provided by the Expo MCP Server MCP server (mattlemmone/file-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.
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