vibekit_write_file · Vibekit MCP: Risk & Policy

WHAT IT DOES

What vibekit_write_file does on Vibekit

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

WHY IT NEEDS A POLICY

Why vibekit_write_file needs a policy

This tool creates or modifies file content, which is a reversible write operation. While files can be overwritten, the action itself is not inherently destructive (data loss is possible but depends on usage context).

From the tool's definition Tool name 'vibekit_write_file' and description 'Write or update a file in an app' explicitly indicate creation or modification of files.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vibekit_write_file Rate-limited

vibekit_write_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": {
    "vibekit_write_file": {
      "limits": [
        {
          "counter": "vibekit_write_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 Vibekit, so you can run agents against it safely.

FAQ

Questions about vibekit_write_file

What does the vibekit_write_file tool do? +

Write or update a file in an app. It is categorised as a Write tool in the Vibekit MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on vibekit_write_file? +

Register the Vibekit MCP server in PolicyLayer and add a rule for vibekit_write_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 Vibekit. Nothing to install.

What risk level is vibekit_write_file? +

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

Can I rate-limit vibekit_write_file? +

Yes. Add a rate_limit block to the vibekit_write_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 vibekit_write_file completely? +

Set action: deny in the PolicyLayer policy for vibekit_write_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 vibekit_write_file? +

vibekit_write_file is provided by the Vibekit MCP server (vibekit-apps/vibekit-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.