Read the contents of a file. Only files inside the configured allowed directories can be read.
AI agents call fs_read_file to retrieve information from Polybridge MCP 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 without modification, deletion, or execution. The lack of side effects, combined with built-in access controls limiting scope to allowed directories, classifies it as a basic Read operation with low severity even in a misuse scenario.
From the tool's definition Tool name 'fs_read_file' and description 'Read the contents of a file' explicitly indicate a retrieval operation with no side effects. The restriction to 'configured allowed directories' further confirms this is a constrained read operation.
Attacks that exploit this kind of access
Read the contents of a file. Only files inside the configured allowed directories can be read. It is categorised as a Read tool in the Polybridge MCP MCP Server, which means it retrieves data without modifying state.
Register the Polybridge MCP server in PolicyLayer and add a rule for fs_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 Polybridge MCP. Nothing to install.
fs_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 fs_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 fs_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.
fs_read_file is provided by the Polybridge MCP server (madjeek-web/polybridge-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.
Teams ship this data inside their own products. See what a licence covers →