update_custom_field

Update a custom field definition label, type, options, required flag, or sort order.

SERVERFavCRM SOURCEhttps://api.favcrm.io/mcp

Medium RISK CLASS

Category Write

Parameters 61 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-favcrm-favcrm/update-custom-field.md

WHAT IT DOES

What update_custom_field does on FavCRM

AI agents use update_custom_field to create or update resources in FavCRM, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your FavCRM environment.

Parameter	Type	Required	Description
`options`	array	—	Allowed values for select/multiselect fields
`fieldType`	string	—	Field type
`sortOrder`	number	—	Display order
`fieldLabel`	string	—	Human-readable label
`isRequired`	boolean	—	Whether this field is required
`definitionId`	string	Yes	Custom field definition ID

Parameters from the server's own tool schema.

RISK

Why update_custom_field is rated Medium

The tool creates or modifies data (custom field metadata) in a reversible manner. It does not delete or permanently destroy data (Destructive), execute arbitrary code (Execute), transfer funds (Financial), or merely read data (Read).

From the tool's definition Tool name 'update_custom_field' and description states it modifies field definition properties: 'label, type, options, required flag, or sort order.' This is a reversible modification operation.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs update_custom_field safely

PolicyLayer is an MCP gateway: it sits between your AI agents and FavCRM, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For update_custom_field, this is the rule to start with:

update_custom_field Rate-limited

update_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.

View as policy code

policy.json

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

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect FavCRM, apply this rule, and every update_custom_field call is checked against it from then on.

FAQ

Questions about update_custom_field

What does the update_custom_field tool do? +

Update a custom field definition label, type, options, required flag, or sort order. It is categorised as a Write tool in the FavCRM MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does update_custom_field accept? +

update_custom_field accepts 6 parameters: options, fieldType, sortOrder, fieldLabel, isRequired, definitionId. Required: definitionId. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on update_custom_field? +

Register the FavCRM MCP server in PolicyLayer and add a rule for update_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 FavCRM. Nothing to install.

What risk level is update_custom_field? +

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

Can I rate-limit update_custom_field? +

Yes. Add a rate_limit block to the update_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.

How do I block update_custom_field completely? +

Set action: deny in the PolicyLayer policy for update_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.

What MCP server provides update_custom_field? +

update_custom_field is provided by the FavCRM MCP server (https://api.favcrm.io/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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