Read the contents of a file
AI agents call readFile 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.
This tool only retrieves data from the filesystem without creating, modifying, or deleting anything. It is a straightforward read operation typical of development and debugging workflows. The severity is low because unauthorized file reads on a development machine expose code and configuration but do not cause irreversible damage or financial harm.
From the tool's definition Tool name is 'readFile' and description states 'Read the contents of a file' — this retrieves file content with no side effects.
Attacks that exploit this kind of access
Read the contents of a file. 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 readFile: 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.
readFile 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 readFile 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 readFile. 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.
readFile 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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