read_file
Read the complete contents of a file as text. DEPRECATED: Use read_text_file instead.
This record as markdown: /tools/filesystem/read-file.md
What read_file does on Filesystem
AI agents call read_file to retrieve information from Filesystem without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
head | number | — | If provided, returns only the first N lines of the file |
path | string | Yes | |
tail | number | — | If provided, returns only the last N lines of the file |
Parameters from the server's own tool schema.
Why read_file is rated Low
This tool retrieves file contents without creating, modifying, deleting, or executing operations. It is purely a read operation with minimal blast radius—the only risk would be unauthorized access to sensitive file contents, but that depends on access controls external to the tool itself.
From the tool's definition Tool name is 'read_file' and description states 'Read the complete contents of a file as text'. The verb 'read' indicates data retrieval with no modification or side effects.
Risk signalsAccepts file system path (path)
Attacks that exploit this kind of access
The rule that runs read_file safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Filesystem, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For read_file, this is the rule to start with:
read_file is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Filesystem, apply this rule, and every read_file call is checked against it from then on.
Questions about read_file
Read the complete contents of a file as text. DEPRECATED: Use read_text_file instead. It is categorised as a Read tool in the Filesystem MCP Server, which means it retrieves data without modifying state.
read_file accepts 3 parameters: head, path, tail. Required: path. The full parameter table on this page comes from the server's own tool schema.
Register the Filesystem MCP server in PolicyLayer and add a rule for read_file: 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 Filesystem. Nothing to install.
read_file 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 read_file 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 read_file. 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.
read_file is provided by the Filesystem MCP server (@modelcontextprotocol/server-filesystem). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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