create_custom_field
Create a custom field definition for CRM entities. Use options for select or multiselect fields.
This record as markdown: /tools/io-favcrm-favcrm/create-custom-field.md
What create_custom_field does on FavCRM
AI agents use create_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 |
fieldName | string | Yes | Stable machine name, e.g. preferred_branch |
fieldType | string | Yes | Field type |
sortOrder | number | — | Display order |
entityType | string | Yes | Entity type, e.g. account, contact, deal, booking |
fieldLabel | string | Yes | Human-readable label, e.g. Preferred branch |
isRequired | boolean | — | Whether this field is required |
Parameters from the server's own tool schema.
Why create_custom_field is rated Medium
This tool creates new field definitions in the CRM system, which modifies the data schema reversibly. It is a Write operation because it creates new metadata structures that can be updated or removed. Severity is medium because misconfiguration could affect data collection and reporting across the CRM, but the impact is limited to schema changes rather than data loss or financial transactions.
From the tool's definition Tool name 'create_custom_field' and description 'Create a custom field definition for CRM entities' indicates data creation/modification.
Attacks that exploit this kind of access
The rule that runs create_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 create_custom_field, this is the rule to start with:
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.
The button opens the PolicyLayer dashboard: create your workspace, connect FavCRM, apply this rule, and every create_custom_field call is checked against it from then on.
Questions about create_custom_field
Create a custom field definition for CRM entities. Use options for select or multiselect fields. 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.
create_custom_field accepts 7 parameters: options, fieldName, fieldType, sortOrder, entityType, fieldLabel, isRequired. Required: fieldName, fieldType, entityType, fieldLabel. The full parameter table on this page comes from the server's own tool schema.
Register the FavCRM 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 FavCRM. 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 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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