[CUSTOM] Calls the Marketo REST API directly (not Adobe's native MCP).
AI agents use custom_update_custom_activity_type 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.
The tool name contains 'update', indicating it modifies an existing custom activity type in Marketo. This is a Write operation as it changes configuration data. Severity is high because modifying activity type definitions can affect how leads and activities are tracked across the entire Marketo instance, potentially breaking downstream workflows, smart campaigns, and reporting.
From the tool's definition 'custom_update_custom_activity_type' — 'update' implies modifying existing data; 'Calls the Marketo REST API directly'
Attacks that exploit this kind of access
[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.
Register the Marketo MCP Server MCP server in PolicyLayer and add a rule for custom_update_custom_activity_type: 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.
custom_update_custom_activity_type is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the custom_update_custom_activity_type 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.
Set action: deny in the PolicyLayer policy for custom_update_custom_activity_type. 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.
custom_update_custom_activity_type 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.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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