Just tested MCP with ChatGPT and had a problem with custom fields.
ChatGPT ist stating:
In the MCP tool POST /v2/posts, customFields is defined as Record<ObjectId, string[]>. However, Featurebase’s API expects a single string for text custom fields.
This makes text fields such as Topic ID and Parent ID impossible to set via MCP: arrays are rejected by the Featurebase API, while single strings are rejected by the MCP schema validation.
Please update the MCP schema to support field-type-specific values, so text fields accept a string and select or multi-select fields use the appropriate value format.
