MCP-free TypeScript library behind Kontor MCP: detect, parse, validate (XSD + official EN 16931 / XRechnung Schematron via Saxon-JS, 89/89 parity with the KoSIT validator), audit with plausibility checks, convert UBL ⇄ CII, generate XRechnung 3.0 UBL and ZUGFeRD 2.3 PDF/A-3, and answer German e-invoicing obligations — all offline, no network, decimal-safe money math.

import { auditInvoice, generateInvoice, validateInvoice } from "@kontor-mcp/core";
const report = await auditInvoice(await fs.readFile("invoice.xml"));
console.log(report.recommendation, report.findings.map((f) => f.ruleId));

Main entry points: detectInvoice, parseInvoice, validateInvoice, auditInvoice / renderAuditText, generateInvoice (target: "zugferd-pdf"), convertInvoice, checkObligations, extractEmbeddedXml, renderHtmlPreview. Standards artefacts come from @kontor-mcp/rules. Docs, conformance evidence and the security posture: the repository README, docs/CONFORMANCE.md, SECURITY.md. Apache-2.0.