custom_update_user · Marketo MCP Server MCP: Risk & Policy

WHAT IT DOES

What custom_update_user does on Marketo MCP Server

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

WHY IT NEEDS A POLICY

Why custom_update_user needs a policy

The tool name strongly suggests updating user records, which is a Write operation. Given the Marketo context (lead and activity management), this likely modifies user/lead attributes. The absence of a description reduces confidence slightly, but the naming convention and server purpose align with reversible data modification rather than destructive or financial operations.

From the tool's definition Tool name 'custom_update_user' indicates modification of user data. The server description confirms it manages Marketo assets including leads and activities. No description provided for this specific tool, limiting certainty.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

custom_update_user Rate-limited

custom_update_user 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": {
    "custom_update_user": {
      "limits": [
        {
          "counter": "custom_update_user_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 Marketo MCP Server, so you can run agents against it safely.

FAQ

Questions about custom_update_user

What does the custom_update_user tool do? +

custom_update_user. It is categorised as a Write tool in the Marketo MCP 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 custom_update_user? +

Register the Marketo MCP Server MCP server in PolicyLayer and add a rule for custom_update_user: 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 Marketo MCP Server. Nothing to install.

What risk level is custom_update_user? +

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

Can I rate-limit custom_update_user? +

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

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

custom_update_user is provided by the Marketo MCP Server MCP server (tyron-pretorius/marketo-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.