update_custom_value

THE RISK

Medium Risk

Why update_custom_value needs a policy

This tool modifies data reversibly—it updates an existing custom value rather than creating new data or deleting it. Updates can typically be undone by applying a different update, making this a Write operation. Severity is medium because misuse could corrupt or alter CRM data fields that affect business operations, but the blast radius is limited to custom value fields and reversible.

From the tool's definition Tool name is 'update_custom_value' with description 'Update an existing custom value'. The verb 'update' indicates modification of existing data in the GoHighLevel CRM system.

Documented attack patterns abuse exactly the kind of access update_custom_value gives an agent:

POLICY

How to control update_custom_value

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 update_custom_value:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_custom_value": {
      "limits": [
        {
          "counter": "update_custom_value_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

update_custom_value 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.

Create a free account and register GoHighLevel MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More GoHighLevel MCP Server tools

Destructive delete_appointment Delete an appointment Destructive delete_contact Delete a contact from GoHighLevel Destructive delete_contact_note Delete a note from a contact Destructive delete_contact_task Delete a task from a contact Destructive delete_custom_field Delete a custom field Destructive delete_custom_value Delete a custom value Destructive delete_opportunity Delete an opportunity from GoHighLevel Destructive delete_user Delete a user

All 64 GoHighLevel MCP Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

Govern customer-ops agents → PII redaction, approval on external messages, and no-bulk-delete rules on the records agents change.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →
PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about update_custom_value

What does the update_custom_value tool do? +

Update an existing custom value. 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.

How do I enforce a policy on update_custom_value? +

Register the GoHighLevel MCP Server MCP server in PolicyLayer and add a rule for update_custom_value: 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.

What risk level is update_custom_value? +

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

Can I rate-limit update_custom_value? +

Yes. Add a rate_limit block to the update_custom_value 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 update_custom_value completely? +

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

update_custom_value 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.

Enforce policy on every GoHighLevel MCP Server tool call.

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.

CHECK YOUR STACK →