Make Timeline fields available in MCP and in-line editing

To add to this, I have been testing what is possible when using MCP to create Timeline entries and found some gaps that would be good to address. The below is a summary of issues as summarised by Claude:

1. Internal Attendees - unpopulatable via API

The field is a Gainsight User lookup. Despite resolving a valid internal user to their Gainsight User GSID, passing it as a custom_field_values entry returns HTTP 500. The expected payload format for user lookup fields is not documented and cannot be determined from the available MCP tooling. The field must be populated manually in the UI.

2. External Attendees - unpopulatable via API

The field is a Contact lookup. Two separate blockers: (a) the Contact object is not queryable via the Gainsight MCP run_query tool, so contact names cannot be resolved to GSIDs programmatically; and (b) even if GSIDs were known, the same HTTP 500 behaviour seen with Internal Attendees suggests the lookup field payload format is the root issue for both. Must be populated manually in the UI.

3. Milestone Type - requires GSID, not display name

Despite the get_activity_types_config tool reporting this field as type STRING, passing the display label (e.g. "Positive Relationship Activity") returns HTTP 500. The field actually requires the Milestone Type object GSID. This is undocumented behaviour and a potential source of significant confusion for anyone building against the MCP. It’s also not scalable if these Milestones Types change as the AI tool needs to be given the fresh info from the Object.

4. Sentiment and Meeting Location - not queryable as columns

Both fields return a P_5005 ("column does not exist") error when included in a fetch_timeline_activity_list select clause. They can be written successfully via custom_field_values but cannot be read back via the query API, making it impossible to verify current values before updating.

5. Contact object not exposed in MCP

run_query does not support the contact object, meaning there is no way to look up external attendee Contact records by name. This blocks any workflow that needs to reference external contacts programmatically.

6. Activity Timeline object not queryable via run_query

The activity_timeline object is not supported by run_query. All timeline reads must go through fetch_timeline_activity_list, which has a more limited and less flexible query interface.

Going to echo the Internal & External Attendee issues/ HTTP 500 behavior. We have a couple of different Timeline types where this is mandatory (including Verified Outcomes); because of this error, the usage of the MCP to log those entries is blocked.

​@rakesh Do we know if this part of any upcoming enhancement?