Backends: PASTA and DataONE¶

Since 2026-07-30 every request to EDI's PASTA+ REST API must be authenticated, including reads of public data¹; an anonymous request gets HTTP 403 ("Public Access … not authorized"). DataONE still serves EDI content anonymously, so edi-mcp has two backends behind one contract:

Each tool produces the same output model from either backend, and every result's source.backend says which one answered: pasta or dataone, or local when no upstream call was made. edi_ping reports the backend that serves the current caller.

A bad key is an error, never a downgrade¶

If a key is configured and PASTA rejects it (HTTP 401), the tool fails with upstream_forbidden; edi-mcp does not quietly retry on DataONE, because a silent downgrade would hide the misconfiguration and change what the results mean. A 403 with valid credentials means the package is restricted to named users or groups; it is also upstream_forbidden, with reason: access_restricted, and a new key will not help. See Utilities and errors.

One deliberate exception keeps answers correct rather than changing their source: PASTA's search indexes only the newest revision of each package, so a DOI of an older revision is resolved through DataONE even with a key, and the result's notes say so.

Key-only operations¶

Some EDI services have no DataONE counterpart: quality reports, provenance (lineage), change and upload feeds, read counts and whole-package zip downloads. The tools planned for them (see the Roadmap) will return auth_required without a key. edi_list_scopes needs PASTA for a live list and falls back to edi-mcp's dated scope snapshot without a key.

Caveats of the DataONE fallback¶

• Lag. The DataONE index can trail new EDI uploads and new revisions by a day or more. Results served from DataONE carry a note saying so.
• Coverage. Not every EDI scope is replicated to DataONE; edi_list_scopes shows DataONE package counts from the snapshot, and a scope with none needs a key.
• Revisions. DataONE's obsolescence links are unreliable, so edi-mcp parses each record's revision from its identifier, keeps the highest revision per package, and reports search totals as an upper bound (totalExact: false).
• Proxying. The member nodes proxy PASTA, so EDI could restrict them in the same way it restricted PASTA.
• Drift. DataONE's index changes without notice: which scopes are replicated, which fields can be sorted, and the order of results for filter-only queries have all changed while edi-mcp was being built. Do not rely on DataONE's result order, and set a key when you need authoritative answers.