{"tool":"gstin-check","title":"GSTIN check (India)","description":"Validate an Indian GSTIN by structure (2-digit state code + PAN + entity code + 'Z') and its mod-36 cross-sum checksum.","method":"POST","call":"/v1/tools/gstin-check/call","input_schema":{"type":"object","required":["gstin"],"properties":{"gstin":{"type":"string","description":"15-character Indian Goods and Services Tax Identification Number."}}},"output_schema":{"type":"object","properties":{"tool":{"type":"string"},"valid":{"type":"boolean"},"normalized":{"type":"string"},"country":{"type":"string"},"reason":{"type":"string"},"scope":{"type":"string"}},"required":["valid","reason"]},"price_usdc_floor":0.000999,"price_note":"dynamic-dutch: live quote via GET /health or the 402 challenge on POST without payment","example_request":{"input":{"gstin":"27AAPFU0939F1ZV"}},"docs":"https://rail.akrivis.in/openapi.json","mcp":"https://rail.akrivis.in/mcp"}