AI agents call get_custom_field to retrieve information from GoHighLevel MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves or queries a specific custom field from the GoHighLevel CRM using its ID. It performs no modifications, deletions, or external operations. The action is read-only and has no destructive capability. Severity is low because disclosure or misuse of this tool would only allow an attacker to view existing custom field data, not modify or delete it.
From the tool's definition Tool name 'get_custom_field' and description 'Get a single custom field by ID' indicate a retrieval operation with no side effects.
Documented attack patterns abuse exactly the kind of access get_custom_field gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and GoHighLevel MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for get_custom_field:
{
"version": "1",
"default": "deny",
"tools": {
"get_custom_field": {}
}
}get_custom_field is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get a single custom field by ID. It is categorised as a Read tool in the GoHighLevel MCP Server MCP Server, which means it retrieves data without modifying state.
Register the GoHighLevel MCP Server MCP server in PolicyLayer and add a rule for get_custom_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 GoHighLevel MCP Server. Nothing to install.
get_custom_field is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_custom_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.
Set action: deny in the PolicyLayer policy for get_custom_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.
get_custom_field is provided by the GoHighLevel MCP Server MCP server (basicmachines-co/open-ghl-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from GoHighLevel MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
64 GoHighLevel MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.