Accessibility (PDF/UA)

Scenario

Produce a PDF a screen reader can read (tagged generation → scoring), or measure whether an incoming PDF has a readable structure. PDF/UA-1 (ISO 14289-1) is inside the spec corpus, so violations can be stated with the clause quoted (T1 — the big difference from PDF/A).

Everything below is a real measurement from 2026-09-04 (pdf-verify-mcp v0.26.0 / veraPDF 1.30.0; tagged demo invoice = the passing side / the Japanese official gazette = the failing side).

Cast

Actor	Role
pdf-writer	Generation with tagged: true, tag_form_fields, ensure_tagged (claim only)
pdf-verify	validate_conformance(pdfua-1) — veraPDF delegation, violations with clause IDs
pdf-reader	inspect_tags (structure tree), extract_structured_text (logical order)
pdf-publish Skill	Producer-side orchestration (tagged implies the pdfua-1 gate)

Sequence

Prompt examples

• "Make this report an accessible PDF, verification included"
• "Can a screen reader read this PDF? What's missing?"
• "Make this form PDF/UA conformant" (→ tag_form_fields)

Measured examples — both sides

Producer side (publish-demo-invoice.pdf): inspect_tags reports tagged, one H1, TH 5 / TD 15 / TR 4. veraPDF 1.30.0 judged PDF/UA-1 COMPLIANT (106/106). The same file is 146/146 under PDF/A-3b.

Auditor side (gazette, 2026-08-10 issue): NOT COMPLIANT — 10 of 106 rules failed (96 passed). The file is encrypted, so veraPDF scored a decrypted rewrite. Principal violations:

Clause (ISO 14289-1)	Violation
7.1-3	236 pieces of real content neither tagged nor marked as Artifact
7.1-11	No StructTreeRoot
6.2-1	No MarkInfo/Marked
7.21.7-1	9 fonts without ToUnicode
7.2-34	Natural language for page content not determined (186 checks)

Call — validate_conformance (pdfua-1)

• Measured: pdf-verify-mcp v0.26.0, veraPDF 1.30.0

Passing side:

{
  "file_path": "/absolute/path/to/docs/specimens/publish-demo-invoice.pdf",
  "flavour": "pdfua-1",
  "response_format": "json"
}

{
  "engine": "verapdf",
  "flavour": "PDF/UA-1",
  "compliant": true,
  "checkedRules": 106,
  "passedRules": 106,
  "failedRules": 0
}

The failing side uses the same arguments with the gazette path: compliant: false, failedRules: 10.

Measured example — the ensure_tagged warning (2026-09-16, second host)

Since pdf-writer-mcp v0.21.1, ensure_tagged returns the same kind of warning as ensure_pdfa, separating "a label was written" from "the score passed" (host Grok Build 1.0.30; pdf-verify-mcp v0.26.1 / veraPDF 1.30.0).

Running ensure_tagged on a Japanese report generated with tagging gave wasTagged: true, createdStructure: false (the structure tree already existed and was left alone), additions limited to Lang / DisplayDocTitle / XMP pdfuaid, and this as warnings[0]:

This file now CLAIMS PDF/UA-1 (pdfuaid:part=1), but conformance was NOT checked here. Only document-level
tagging requirements were supplied; reading order, alternative text, and similar PDF/UA rules are left as they are.

validate_conformance (pdfua-1) on the same file: veraPDF 106/106, with the note that the meaning of alt text and reading order cannot be judged by machine. The untagged control file scored 99/106, failing 7.1-3, 7.2-34, 7.1-10, 7.1-11, 7.21.4.1-1, 6.2-1 and 7.1-8. pdf-spec's get_requirements (pdfua1, §7.1, shall) returned 10 clauses; R-7.1-3 (semantically appropriate tags and logical order) is the clause behind the failure.

Still open: create_markdown_pdf (tagged) produces two H1 elements when the title and the first heading are the same string. veraPDF passes it, but the heading appears twice in extract_structured_text.

Full report: eval/hosts/grok-build/reports/UC04.md (Japanese)

How to read the results

• PDF/UA-1 is T1 — a violation can be stated as "ISO 14289-1 7.1-3 requires…", one step stronger than PDF/A's "veraPDF judged it so"
• Native-engine violations carry a severity: only error proves non-conformance (warnings need human review)
• With tagged: true, an embedded font and a title are mandatory even without CJK text (the standard 14 fonts always violate 7.21.4.1)
• Machines validate structure only. Whether alt text is meaningful and the reading order is natural remains human review
• ensure_tagged writes a label — once used, pdfua-1 must be measured