# set_custom_field_values

Set or clear custom field values for a CRM entity. Values are stored as strings; pass null to clear a value.

Agent View of the PolicyLayer registry record for `set_custom_field_values`. HTML page: https://policylayer.com/tools/io-favcrm-favcrm/set-custom-field-values

## Facts

- Tool: `set_custom_field_values`
- Server: FavCRM (`https://api.favcrm.io/mcp`) — https://policylayer.com/tools/io-favcrm-favcrm.md
- Homepage: https://github.com/favcrm/mcp
- Risk category: Write (Medium risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server CORS policy: *
- Server rate-limited: no
- Parameters: 3 (3 required)
- Recommended policy verdict: Rate-limited

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `values` | array | yes | Values to upsert |
| `entityId` | string | yes | Entity ID |
| `entityType` | string | yes | Entity type |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "set_custom_field_values",
    "arguments": {
      "values": [],
      "entityId": "<entityId>",
      "entityType": "<entityType>"
    }
  }
}
```

## Why set_custom_field_values is rated Medium

This tool modifies CRM entity data (custom field values) but the changes are reversible—values can be updated or cleared without permanent deletion. This fits the Write category.

From the tool's own definition: "Tool description states 'Set or clear custom field values for a CRM entity,' explicitly performing create/modify operations on CRM data that are reversible (values can be cleared by passing null)."

## Use case

AI agents use set_custom_field_values 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.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches FavCRM:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_custom_field_values": {
      "limits": [
        {
          "counter": "set_custom_field_values_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on FavCRM (219)

- `cancel_booking` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/cancel-booking.md
- `delete_account` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-account.md
- `delete_campaign` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-campaign.md
- `delete_category` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-category.md
- `delete_contact` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-contact.md
- `delete_custom_field` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-custom-field.md
- `delete_deal` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-deal.md
- `delete_invoice` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-invoice.md
- `delete_knowledge_document` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-knowledge-document.md
- `delete_post` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-post.md
- `delete_post_type` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-post-type.md
- `delete_post_type_field` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-post-type-field.md
- `delete_promotion` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-promotion.md
- `delete_segment` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-segment.md
- `delete_service_package` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-service-package.md
- `delete_tag` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-tag.md
- `delete_task` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/delete-task.md
- `remove_post_block` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/remove-post-block.md
- `void_invoice` — Destructive — https://policylayer.com/tools/io-favcrm-favcrm/void-invoice.md
- `execute_tool` — Execute — https://policylayer.com/tools/io-favcrm-favcrm/execute-tool.md
- `switch_company` — Execute — https://policylayer.com/tools/io-favcrm-favcrm/switch-company.md
- `cancel_subscription` — Financial — https://policylayer.com/tools/io-favcrm-favcrm/cancel-subscription.md
- `create_plan_upgrade_link` — Financial — https://policylayer.com/tools/io-favcrm-favcrm/create-plan-upgrade-link.md
- `create_subscription` — Financial — https://policylayer.com/tools/io-favcrm-favcrm/create-subscription.md
- `enrol_membership` — Financial — https://policylayer.com/tools/io-favcrm-favcrm/enrol-membership.md
- `record_invoice_payment` — Financial — https://policylayer.com/tools/io-favcrm-favcrm/record-invoice-payment.md
- `check_plan_operation` — Read — https://policylayer.com/tools/io-favcrm-favcrm/check-plan-operation.md
- `get_attachment_text` — Read — https://policylayer.com/tools/io-favcrm-favcrm/get-attachment-text.md
- `get_audit_log` — Read — https://policylayer.com/tools/io-favcrm-favcrm/get-audit-log.md
- `get_available_slots` — Read — https://policylayer.com/tools/io-favcrm-favcrm/get-available-slots.md
- …and 189 more: https://policylayer.com/tools/io-favcrm-favcrm.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-favcrm-favcrm · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-favcrm-favcrm