Error: no 'docdata' section
You attached GSTR-2A, GSTR-1 or the summary file. Download GSTR-2B > Download JSON again.
Error: no header with a GSTIN column
Rename your register headers to GSTIN and Supplier Invoice No (or Invoice No), then run again.
Many bills show missing on both sides
Your register uses a different bill number than the supplier's (for example your voucher number). Export the supplier invoice number column.
A register line is listed as skipped
Its amount is not a number (for example '5k'). Fix that cell and run again.
Claude does not use the skill
Check it is switched on in Settings → Capabilities → Skills, then name it in your message.
The script says a column is missing
Rename your header to one of the names in README, or say the mapping in your message.
Code execution is off
Skills with scripts need code execution enabled in Claude.ai settings.
FAQ
Does it log in to the GST portal? No. You download the GSTR-2B JSON yourself and attach it. It never asks for your password, OTP or any API key.
Which purchase registers work? Any CSV or Excel export with a GSTIN column, a supplier invoice number column and IGST and/or CGST/SGST columns. Tally, Zoho Books and Busy exports usually have these headers.
Is the free version limited? One GSTR-2B month per run with exact bill-number matching. No account and no monthly cap.
Can I claim ITC from this report? It is matching help for your records, not tax advice. Your CA decides what ITC to claim.