custom_create_lead_fields · Marketo MCP Server MCP

WHAT IT DOES

What custom_create_lead_fields does on Marketo MCP Server

AI agents use custom_create_lead_fields 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_create_lead_fields needs a policy

This tool creates new lead field definitions in Marketo, which is a write operation that modifies the system structure. While reversible (fields can typically be deleted or modified), the impact is moderate—incorrect field creation could affect data collection, reporting, and downstream integrations.

From the tool's definition Tool name 'custom_create_lead_fields' indicates creation of lead field definitions. Description states it 'Calls the Marketo REST API directly,' and the server context shows this is part of a tool set for 'comprehensive management of Marketo assets including…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

custom_create_lead_fields Rate-limited

custom_create_lead_fields 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_create_lead_fields": {
      "limits": [
        {
          "counter": "custom_create_lead_fields_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_create_lead_fields

What does the custom_create_lead_fields tool do? +

[CUSTOM] Calls the Marketo REST API directly (not Adobe's native MCP). 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_create_lead_fields? +

Register the Marketo MCP Server MCP server in PolicyLayer and add a rule for custom_create_lead_fields: 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_create_lead_fields? +

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

Can I rate-limit custom_create_lead_fields? +

Yes. Add a rate_limit block to the custom_create_lead_fields 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_create_lead_fields completely? +

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

custom_create_lead_fields 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.