GetTypeInfo returns HTTP 406 for data elements — no way to read a DTEL (Accept header, cf. #9)

[gorynychzmey]

Summary

GetTypeInfo targets the correct ADT endpoint for a data element, but the request is rejected with HTTP 406 (ExceptionResourceNotAcceptable). Combined with GetSource not supporting DTEL at all, there is currently no tool-based way to read a data element.

This looks like the same class of bug as the closed #9 ("Transport API returns 406 - Wrong Accept header for CTS endpoints"), just on a different endpoint family.

Environment

• vsp version: 2.38.1 (commit a75fbfd9edf742507671dcc0334544c2c39a68d5, built 2026-04-07)
• OS: Windows 11, stdio MCP transport
• Mode: --mode expert, with --enable-transports --allow-transportable-edits
• Backend: SAP ERP 6.0, non-HANA (feature probe reports hana: false)
• Note: this is a different backend family from Transport API returns 406 - Wrong Accept header for CTS endpoints #9/get_user_transports returns empty while list_transports returns same data (follow-up to #9) #111 (S/4HANA 2023), so the 406 is not S/4-specific.

Reproduction

GetTypeInfo { "type_name": "SAEOBJECT" }

Result:

Failed to get type info: getting type info: ADT API error: status 406
at /sap/bc/adt/ddic/dataelements/SAEOBJECT:
<exc:exception xmlns:exc="http://www.sap.com/abapxml/types/communicationframework">
  <namespace id="com.sap.adt"/>
  <type id="ExceptionResourceNotAcceptable"/>
  <message lang="EN">The message content is not acceptable</message>
  <properties>
    <entry key="T100KEY-ID">SADT_RESOURCE</entry>
    <entry key="T100KEY-NO">037</entry>
  </properties>
</exc:exception>

SAEOBJECT is a standard SAP data element and definitely exists.

Why this looks like a client-side bug

The URL /sap/bc/adt/ddic/dataelements/SAEOBJECT is correct and the object exists. SAP answers ExceptionResourceNotAcceptable (SADT_RESOURCE/037) — that is content negotiation failing, i.e. the Accept header sent does not match what the endpoint offers. This is exactly the failure mode diagnosed and fixed in #9 for the CTS endpoints.

GetFunctionGroup fails the same way on namespaced groups (filed separately).

Expected

Return the data element definition — data type, length, decimals, domain and description.

Verification that the data is reachable

The same information is available through RunQuery without any problem, which confirms it is an ADT-request issue rather than missing authorization or a missing object:

SELECT a~rollname, a~domname, a~datatype, a~leng, a~decimals, b~ddtext
  FROM dd04l AS a INNER JOIN dd04t AS b
    ON b~rollname = a~rollname AND b~ddlanguage = 'D'
 WHERE a~rollname = 'SAEOBJECT'

→ CHAR, length 10, domain SADC10, "SAP ArchiveLink: Objekttyp".

Additional note

GetSource rejects DTEL outright:

GetSource failed: unsupported object type: DTEL
(supported: PROG, CLAS, INTF, FUNC, FUGR, INCL, DDLS, VIEW, BDEF, SRVD, SRVB, MSAG)

So neither tool can currently read a data element. Supporting DTEL in GetSource would be a reasonable alternative fix.