# Task ID: 12
# Title: Implement Custom Fields Endpoints
# Status: pending
# Dependencies: 5, 8
# Priority: low
# Description: Create MCP tools for managing custom fields, including listing, creating, and deleting custom fields.
# Details:
1. Create a 'custom-fields' module in src/tools/
2. Implement 'motion_list_custom_fields' tool
3. Create 'motion_create_custom_field' with support for various field types
4. Implement 'motion_delete_custom_field' tool
5. Add 'motion_assign_custom_field' for managing field assignments to projects and tasks
6. Use Zod for input validation in all tools
# Test Strategy:
1. Unit test each custom field management tool
2. Test creation of different custom field types
3. Verify proper assignment of custom fields to projects and tasks
4. Integration test with mock API responses
