custom_update_lead_field · Marketo MCP Server MCP

WHAT IT DOES

What custom_update_lead_field does on Marketo MCP Server

AI agents use custom_update_lead_field 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_lead_field needs a policy

This tool modifies lead data fields, making it a Write category operation. Severity is high because lead records are critical business assets in marketing automation; a misused update could corrupt contact information, segmentation data, or campaign eligibility across potentially thousands of records.

From the tool's definition Tool name 'custom_update_lead_field' explicitly performs field updates on leads. Description states it 'Calls the Marketo REST API directly' for lead field modification.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

custom_update_lead_field Rate-limited

custom_update_lead_field 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_lead_field": {
      "limits": [
        {
          "counter": "custom_update_lead_field_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_lead_field

What does the custom_update_lead_field 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_update_lead_field? +

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

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

Can I rate-limit custom_update_lead_field? +

Yes. Add a rate_limit block to the custom_update_lead_field 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_lead_field completely? +

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

custom_update_lead_field 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.