Remediate PDF

Nutrient Remediate PDF

Remediate an existing PDF by auto-tagging it with PDF/UA semantic structure — headings (H1–H6), lists, tables (TR/TD/TH), reading order, and artifact marking — via the dedicated Nutrient DWS Accessibility API. The script uploads a PDF and writes back the remediated, tagged PDF.

This skill ships auto-tag only. The DWS Accessibility API does not currently expose a separate accessibility conformance validation endpoint (confirmed by live probe — see references/accessibility-api-reference.md). To check tagged output today, use the bundled standalone verifier — uv run scripts/verify-pdf.py --input doc-tagged.pdf --profile pdfua — which checks structural PDF/UA-1 signals and escalates to a full veraPDF audit when veraPDF is installed. It is not a certification. (The same verifier ships with the make-pdf skill.)

When to use

• "Make this PDF accessible" / "auto-tag for screen readers"
• "Tag this PDF for PDF/UA" / "remediate accessibility"
• "Prepare this document for Section 508" (the tagging step)

Disambiguation from sibling skills

Existing PDF vs. new PDF is the first fork:

• Use this skill (remediate-pdf) to fix a PDF that already exists — auto-tag it for accessibility.
• Use make-pdf (its own plugin: /plugin install make-pdf@nutrient-skills) to generate a NEW compliant PDF from Markdown or HTML (PDF/UA or PDF/A output with built-in verification). This plugin bundles the same verify-pdf.py for checking tagged output.

Both document-processor-api and this skill perform PDF/UA auto-tagging using the same underlying engine (the pdf_to_pdfua capability — confirmed from the live response's build stats). The distinction is product and account surface, not capability:

• Use this skill (remediate-pdf) when the user wants the dedicated DWS Accessibility product: its own API key (NUTRIENT_ACCESSIBILITY_API_KEY), its own monthly auto-tagged-pages quota and dashboard.
• Use document-processor-api when the user is already doing /build work and wants PDF/UA as one of several output targets with their Processor key, or wants convert to PDF/A, produce PDF/UA via /build, merge, or sign.

Do not claim the Processor "cannot auto-tag" — it can. Route on which product/key/quota the user wants, not on a capability difference. Cross-link the Processor's pdfua output target.

Setup

The DWS Accessibility API is a separate product with its own API key (distinct from the Processor key NUTRIENT_API_KEY and the Extraction key NUTRIENT_EXTRACT_API_KEY). Calling the Accessibility endpoint with the wrong product key returns 401 (malformed/unknown key) or 403 (valid key for a different DWS product — observed live).

• Get a DWS Accessibility API key at https://dashboard.nutrient.io/.
• Export it as NUTRIENT_ACCESSIBILITY_API_KEY (the key uses the pdf_live_ prefix):

  export NUTRIENT_ACCESSIBILITY_API_KEY="pdf_live_..."
  

• Run from the directory containing this SKILL.md:

  cd <directory containing this SKILL.md> && uv run scripts/autotag.py --help
  

Operations

autotag.py — remediate a PDF with PDF/UA tags

uv run scripts/autotag.py --input doc.pdf --output doc-tagged.pdf
uv run scripts/autotag.py --url https://example.com/doc.pdf --output doc-tagged.pdf

• POST https://api.nutrient.io/accessibility/autotag, Authorization: Bearer <key>, always as multipart/form-data (field file). --url is validated (https-only, must resolve to a public address) then downloaded client-side and uploaded as bytes — the Nutrient backend never fetches the URL, so there is no backend SSRF surface (redirects are not followed).
• On success the remediated PDF is written to --output (default <input-stem>-tagged.pdf).
• The script prints the pages-processed and quota-unit count from the response build stats.

Decision rules

• Quota gate. Auto-tagging consumes from the monthly auto-tagged-pages quota (Free tier = 20 pages/month; quotas do not roll over and the API blocks at the limit). autotag.py estimates the page count and requires confirmation before any run exceeding remaining quota (when the account surfaces it) or exceeding --confirm-over (default 20) when remaining is unknown. Pass --yes to bypass for known-safe runs.
• Max file size is 150 MiB per request; the script enforces this client-side before upload. For larger documents, split first with document-processor-api/split.py.
• Do not auto-retry on a 2xx response — each call consumes quota.

Anti-patterns

• Do not represent auto-tagged output as guaranteed PDF/UA-compliant. Auto-tagging improves but does not guarantee conformance (Nutrient's benchmark cites ~96.5% PDF/UA conformance, not 100%). Check output with the bundled verify-pdf.py (and veraPDF for a full audit); treat the output as remediated, not certified.
• Do not route convert to PDF/A, produce PDF/UA via /build, merge, or sign here — those belong to document-processor-api.
• Do not use a Processor or Extraction key against this endpoint — it returns 401.

Security Hardening Addendum

• Never store NUTRIENT_ACCESSIBILITY_API_KEY in committed files. Use process env injection at runtime (shell/export, secrets manager, or host env).
• The script never prints or logs the API key, and redacts the key from any error response body before printing it.
• --url inputs are validated (https-only; the host must resolve to a globally-routable public address) and then fetched client-side with redirects disabled, so the Nutrient backend never fetches the URL — there is no backend SSRF surface. The client fetch is still operator-scoped egress: do not pass unsanitized user-controlled strings to --url.

Reference map

• references/accessibility-api-reference.md — confirmed endpoint, request/response shape, quota model, error envelope, and the validation-endpoint probe findings.
• references/pdf-ua-wcag-compliance-notes.md — what PDF/UA auto-tagging does, PDF/UA vs WCAG, Section 508 relationship.
• Sibling document-processor-api/SKILL.md — /build PDF/UA output target and the same underlying auto-tagging engine.
• scripts/verify-pdf.py — the bundled standalone structural checker for tagged output (the identical file ships in the make-pdf plugin; keep them in sync).
• The make-pdf skill (separate plugin: make-pdf@nutrient-skills) — generate NEW compliant PDFs from Markdown/HTML.