# list_custom_fields List custom field definitions for CRM entities such as account, contact, deal, or booking. Agent View of the PolicyLayer registry record for `list_custom_fields`. HTML page: https://policylayer.com/tools/io-favcrm-favcrm/list-custom-fields ## Facts - Tool: `list_custom_fields` - Server: FavCRM (`https://api.favcrm.io/mcp`) — https://policylayer.com/tools/io-favcrm-favcrm.md - Homepage: https://github.com/favcrm/mcp - Risk category: Read (Low risk) - Registry record: grade F, identity unverified - Server auth posture: open - Server CORS policy: * - Server rate-limited: no - Parameters: 1 (1 required) - Recommended policy verdict: Allowed ## Parameters | Parameter | Type | Required | Description | | --- | --- | --- | --- | | `entityType` | string | yes | Entity type the custom fields belong to | 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": "list_custom_fields", "arguments": { "entityType": "" } } } ``` ## Why list_custom_fields is rated Low This tool queries and retrieves custom field definitions for CRM entities. It performs a read-only operation that retrieves configuration/metadata without creating, modifying, deleting, or executing any changes to data. The blast radius of misuse is minimal—an agent could only discover the schema of custom fields, not access sensitive customer data or perform destructive actions. From the tool's own definition: "Tool name contains 'list' and description states 'List custom field definitions' — a retrieval operation with no side effects. Returns metadata about CRM entity structure." ## Use case AI agents call list_custom_fields to retrieve information from FavCRM without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere. ## Recommended policy (PolicyLayer) Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches FavCRM: ```json { "version": "1", "default": "deny", "tools": { "list_custom_fields": {} } } ``` ## 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` --- 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