returns_update_custom_fields
AI agents use returns_update_custom_fields to create or update resources in ServiceTitan MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your ServiceTitan MCP Server environment.
An AI agent can call returns_update_custom_fields faster than any human can review — one bad instruction and it creates or modifies resources in ServiceTitan MCP Server by the hundred, each call as confident as the last.
Attacks that exploit this kind of access
returns_update_custom_fields. It is categorised as a Write tool in the ServiceTitan MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the ServiceTitan MCP Server MCP server in PolicyLayer and add a rule for returns_update_custom_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 ServiceTitan MCP Server. Nothing to install.
returns_update_custom_fields 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 returns_update_custom_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.
Set action: deny in the PolicyLayer policy for returns_update_custom_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.
returns_update_custom_fields is provided by the ServiceTitan MCP Server MCP server (jordandalton/servicetitanmcpserver). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.