replace_in_file · MCP File Editor Server MCP: Risk & Policy

WHAT IT DOES

What replace_in_file does on MCP File Editor Server

AI agents use replace_in_file to create or update resources in MCP File Editor Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP File Editor Server environment.

WHY IT NEEDS A POLICY

Why replace_in_file needs a policy

This tool creates reversible changes to file content through pattern matching and replacement. While the replacement is applied broadly ('all occurrences'), it does not delete files or irreversibly remove data — the original content could be restored via version control or undo mechanisms. This makes it Write rather than Destructive.

From the tool's definition Tool performs regex-based replacement of content in files, which modifies file data. Description states 'Replace all occurrences of a regex pattern with a target string in a file' — a direct content modification operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

replace_in_file Rate-limited

replace_in_file stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "replace_in_file": {
      "limits": [
        {
          "counter": "replace_in_file_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches MCP File Editor Server, so you can run agents against it safely.

FAQ

Questions about replace_in_file

What does the replace_in_file tool do? +

Replace all occurrences of a regex pattern with a target string in a file. It is categorised as a Write tool in the MCP File Editor Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on replace_in_file? +

Register the MCP File Editor Server MCP server in PolicyLayer and add a rule for replace_in_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 MCP File Editor Server. Nothing to install.

What risk level is replace_in_file? +

replace_in_file is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit replace_in_file? +

Yes. Add a rate_limit block to the replace_in_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.

How do I block replace_in_file completely? +

Set action: deny in the PolicyLayer policy for replace_in_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.

What MCP server provides replace_in_file? +

replace_in_file is provided by the MCP File Editor Server MCP server (pwilkin/mcp-file-edit). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.