Create a new custom field in a location
AI agents use create_custom_field to create or update resources in GoHighLevel MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your GoHighLevel MCP Server environment.
Creating a custom field is a reversible write operation that adds a new data structure to the CRM. It modifies configuration rather than destroying data, and does not execute arbitrary code or move funds. While it affects the system structure, the field can typically be removed if needed.
From the tool's definition Tool description states it will "Create a new custom field in a location" — this is a create operation that modifies the CRM schema/configuration by adding a new field.
Documented attack patterns abuse exactly the kind of access create_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 create_custom_field:
{
"version": "1",
"default": "deny",
"tools": {
"create_custom_field": {
"limits": [
{
"counter": "create_custom_field_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_custom_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.
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Create a new custom field in a location. It is categorised as a Write tool in the GoHighLevel MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the GoHighLevel MCP Server MCP server in PolicyLayer and add a rule for create_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.
create_custom_field 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 create_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 create_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.
create_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.