Search for a regex pattern within files in a specified directory (read-only). Returns matches and any errors encountered.
AI agents call search_files to retrieve information from Filesystem without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a search operation that queries file contents and returns matching results. It has no side effects, does not modify data, does not execute code, and does not delete anything. It is a classic Read category operation with minimal blast radius if misused by an AI agent—worst case would be scanning files it shouldn't have access to, but no system state is changed.
From the tool's definition Tool description explicitly states 'read-only' and 'search for a regex pattern within files', which retrieves data without modification.
Documented attack patterns abuse exactly the kind of access search_files gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Filesystem, and nothing reaches the server without passing your rules. This is the rule we recommend for search_files:
{
"version": "1",
"default": "deny",
"tools": {
"search_files": {}
}
}search_files is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Search for a regex pattern within files in a specified directory (read-only). Returns matches and any errors encountered. It is categorised as a Read tool in the Filesystem MCP Server, which means it retrieves data without modifying state.
Register the Filesystem MCP server in PolicyLayer and add a rule for search_files: 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.
search_files 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 search_files 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 search_files. 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.
search_files is provided by the Filesystem MCP server (sylphxai/filesystem-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Filesystem, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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13 Filesystem tools catalogued and risk-classified — across an index of 43,000+ MCP servers.