update_output_preferences · VIN MCP: Risk & Policy

WHAT IT DOES

What update_output_preferences does on VIN MCP

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

WHY IT NEEDS A POLICY

Why update_output_preferences needs a policy

This tool creates or modifies user-specific configuration data (output preferences) in a reversible manner. It does not retrieve data (Read), execute arbitrary operations (Execute), delete data irreversibly (Destructive), or move money (Financial). The blast radius is minimal since preference changes affect only report formatting and can be easily reverted.

From the tool's definition Tool name 'update_output_preferences' and description 'Update which sections appear in VIN reports' indicate modification of user preferences or settings.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_output_preferences Rate-limited

update_output_preferences 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": {
    "update_output_preferences": {
      "limits": [
        {
          "counter": "update_output_preferences_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

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

FAQ

Questions about update_output_preferences

What does the update_output_preferences tool do? +

Update which sections appear in VIN reports. It is categorised as a Write tool in the VIN MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_output_preferences? +

Register the VIN MCP server in PolicyLayer and add a rule for update_output_preferences: 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 VIN MCP. Nothing to install.

What risk level is update_output_preferences? +

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

Can I rate-limit update_output_preferences? +

Yes. Add a rate_limit block to the update_output_preferences 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 update_output_preferences completely? +

Set action: deny in the PolicyLayer policy for update_output_preferences. 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 update_output_preferences? +

update_output_preferences is provided by the VIN MCP server (keptlive/vin-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.