pdfnative-mcp

Prepare signature placeholder

prepare_signature_placeholder

Idempotent

Creates an unsigned PDF with a /Sig placeholder for a later sign_pdf call. Pre-sizes /Contents, pins the widget page, and freezes signer details before signing.

Instructions

New PDF carrying an unsigned /Sig placeholder for a LATER sign_pdf call. OPTIONAL — sign_pdf auto-injects one. Use it to size the placeholder (placeholderBytes for > 4096-bit keys, reserveTimestamp for an RFC 3161 token), to pin the widget page (pageIndex), to choose subFilter 'ETSI.CAdES.detached' (PAdES), or to ship the placeholder separately. signerName/reason/location/contactInfo/signingTime are frozen into /Sig here — sign_pdf cannot rewrite them later. NOTE: the unsigned file is not yet a conformant PDF/A (empty /Contents); it becomes one once signed. PDF/A, print, metadata and creationDate options as on every document tool.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`pdfA`	No	PDF/A level: pdfa1b (simple text+images), pdfa2b/pdfa2u (richer; 2u = Unicode mapping), pdfa3b (attachments / Factur-X). Pair with embedFonts=true for a valid claim. Exclusive with encryption. See docs/guides/PDFA.md. The unsigned placeholder is NOT yet conformant (empty /Contents, ISO 19005-2 §6.4.3); it is once signed with sign_pdf profile:'pades'.
`debug`	No	Draw margin / block / cell guide rectangles (unmarked content — not for PDF/UA output). Geometry unchanged. Default false.
`print`	No	Print production (ISO 32000-1 §14.11): page boxes, `bleed` shorthand (TrimBox = MediaBox inset), crop/registration marks outside the TrimBox, /UserUnit for large formats (PDF 1.7; not under pdfa1b). See docs/guides/PRINT.md.
`title`	Yes	Document title. Used as the PDF metadata title and rendered at the top of page 1.
`blocks`	No	Optional document body blocks rendered before the signature field.
`reason`	No	Reason for signing (e.g. "Approved", "I agree to the terms").
`strict`	No	Fail instead of producing a file the engine warns about: a PDFA_* diagnostic → PDF_A_COMPLIANCE_VIOLATION (e.g. PDFA_NO_FONT_ENTRIES without embedFonts), a PDFX_* one → PDF_X_COMPLIANCE_VIOLATION, any other → DIAGNOSTIC_ESCALATED. Pair with embedFonts=true.
`margins`	No	Margins in points, all four required (0–200). Default 45 / 36 / 35 / 36.
`compress`	No	FlateDecode the streams (smaller file, different bytes; PDF/A unaffected, XMP stays plain). Default false.
`location`	No	Signing location (city / country).
`metadata`	No	/Info (+ XMP under PDF/A): author, subject, keywords, /Trapped.
`pageSize`	No	Portrait page preset (points): A4 595.28×841.89 (default), Letter 612×792, Legal 612×1008, A3 841.89×1190.55, Tabloid 792×1224. print.* boxes must fit it.
`fieldName`	No	Optional AcroForm field name for the signature widget (default 'Signature1').
`pageIndex`	No	Zero-based page index the (invisible) widget attaches to (default 0).
`subFilter`	No	Signature SubFilter baked into the /Sig dictionary (frozen at placeholder time). Use 'ETSI.CAdES.detached' for PAdES baseline signatures (sign_pdf profile='pades'). Default 'adbe.pkcs7.detached'.
`embedFonts`	No	Embed Noto Sans Latin instead of the viewer base-14 Helvetica. REQUIRED for a valid PDF/A or PDF/X claim (every font embedded) and for strict=true; adds ~0.3 MiB.
`outputMode`	No	Either 'base64' (returns the PDF inline) or 'file' (writes to a sandboxed path inside PDFNATIVE_MCP_OUTPUT_DIR).	base64
`outputPath`	No	Required when outputMode='file'. Relative path inside the sandbox; must end with .pdf.
`signerName`	No	Name of the intended signer, embedded in the /Sig dictionary.
`typography`	No	Fine typography, all opt-in (omitted = unchanged bytes). kerning, fontFeatures and the 'fr' narrow space need embedFonts:true. No hyphenation dictionary is installed: use soft hyphens (U+00AD). See the typography prompt.
`contactInfo`	No	Contact information for the signer.
`signingTime`	No	/Sig /M — the claimed signing instant (ISO-8601), frozen into the placeholder dictionary. Omitted: the wall clock at placeholder time. Pin it (with creationDate) for byte-identical output across calls.
`creationDate`	No	ISO-8601 instant for /CreationDate (+ XMP, the trailer /ID and the {date} placeholder), written in UTC. Pin it for byte-identical output across calls and hosts; omitted = wall clock, so every call differs.
`outputIntent`	No	Custom OutputIntent (under pdfA or pdfx): an RGB, CMYK or Gray ICC profile + condition strings, replacing the built-in sRGB intent. The profile must be a real ICC file ('acsp' signature, consistent size — PRINT_ERROR otherwise); pdfx needs device class 'prtr'. Under a CMYK / Gray intent RGB content is mapped through a calibrated default space.
`footerTemplate`	No	Running footer on every page. Replaces the default footer: footerText is then ignored and page numbers appear only via {page}/{pages}.
`headerTemplate`	No	Running header on every page (left / center / right zones); reserves 15 pt.
`placeholderBytes`	No	Reserved bytes for the future CMS /Contents blob (default 16384; 24576 when reserveTimestamp=true). Increase only for >4096-bit RSA, long chains or large TSA tokens.
`reserveTimestamp`	No	Reserve room for an RFC 3161 signature timestamp (sign_pdf timestamp=true): adds 8 KiB to the default placeholder size. Ignored when placeholderBytes is set explicitly.
`includeDiagnostics`	No	Return the diagnostics raised while building (PDFA_, PDFX_, TYPOGRAPHY_*) as `diagnostics[]` (possibly empty).

Output Schema

TableJSON Schema

Name	Required	Description
`mode`	Yes
`summary`	No	Tool-specific summary, when produced.
`filePath`	No	Sandboxed absolute path (file mode).
`sizeBytes`	Yes
`diagnostics`	No	Engine diagnostics (when includeDiagnostics=true).

Schema Changelog

Changes observed during successful MCP inspections.

Changed23 schema fields changedv1.6.2Sep 27, 2026

changedInput schema / properties / creationDate / description

Previous value: -"ISO-8601 instant for /CreationDate (+ XMP). Pin it for byte-identical output across calls (same host TZ); omitted = wall clock, so every call differs."New value: +"ISO-8601 instant for /CreationDate (+ XMP, the trailer /ID and the {date} placeholder), written in UTC. Pin it for byte-identical output across calls and hosts; omitted = wall clock, so every call differs."

changedInput schema / properties / embedFonts / description

Previous value: -"Embed Noto Sans Latin instead of the viewer base-14 Helvetica. REQUIRED for a valid PDF/A claim (ISO 19005 §6.2.11.4.1) and for strict=true; adds ~0.3 MiB."New value: +"Embed Noto Sans Latin instead of the viewer base-14 Helvetica. REQUIRED for a valid PDF/A or PDF/X claim (every font embedded) and for strict=true; adds ~0.3 MiB."

changedInput schema / properties / footerTemplate / properties / center / description

Previous value: -"Placeholders: {page} {pages} {title} {date} (build-day wall clock, not creationDate)."New value: +"Placeholders: {page} {pages} {title} {date} (UTC date of creationDate when pinned, else of the build)."

addedInput schema / properties / footerTemplate / properties / color / anyOf

Added value: +[
+  {
+    "pattern": "^#[0-9a-fA-F]{6}$",
+    "type": "string"
+  },
+  {
+    "description": "DeviceCMYK operands 'C M Y K', each 0.0–1.0.",
+    "pattern": "^(?:0(?:\\.\\d+)?|1(?:\\.0+)?)(?: (?:0(?:\\.\\d+)?|1(?:\\.0+)?)){3}$",
+    "type": "string"
+  },
+  {
+    "description": "DeviceCMYK ink percentages [c, m, y, k], each 0–100.",
+    "items": {
+      "maximum": 100,
+      "minimum": 0,
+      "type": "number"
+    },
+    "maxItems": 4,
+    "minItems": 4,
+    "type": "array"
+  }
+]

changedInput schema / properties / footerTemplate / properties / color / description
```
Previous value: -"Hex colour."New value: +"Hex colour (#RRGGBB)."
```
removedInput schema / properties / footerTemplate / properties / color / pattern
```
Removed value: -"^#[0-9a-fA-F]{6}$"
```
removedInput schema / properties / footerTemplate / properties / color / type
```
Removed value: -"string"
```

changedInput schema / properties / footerTemplate / properties / left / description

Previous value: -"Placeholders: {page} {pages} {title} {date} (build-day wall clock, not creationDate)."New value: +"Placeholders: {page} {pages} {title} {date} (UTC date of creationDate when pinned, else of the build)."

changedInput schema / properties / footerTemplate / properties / right / description

Previous value: -"Placeholders: {page} {pages} {title} {date} (build-day wall clock, not creationDate)."New value: +"Placeholders: {page} {pages} {title} {date} (UTC date of creationDate when pinned, else of the build)."

changedInput schema / properties / headerTemplate / properties / center / description

Previous value: -"Placeholders: {page} {pages} {title} {date} (build-day wall clock, not creationDate)."New value: +"Placeholders: {page} {pages} {title} {date} (UTC date of creationDate when pinned, else of the build)."

addedInput schema / properties / headerTemplate / properties / color / anyOf

Added value: +[
+  {
+    "pattern": "^#[0-9a-fA-F]{6}$",
+    "type": "string"
+  },
+  {
+    "description": "DeviceCMYK operands 'C M Y K', each 0.0–1.0.",
+    "pattern": "^(?:0(?:\\.\\d+)?|1(?:\\.0+)?)(?: (?:0(?:\\.\\d+)?|1(?:\\.0+)?)){3}$",
+    "type": "string"
+  },
+  {
+    "description": "DeviceCMYK ink percentages [c, m, y, k], each 0–100.",
+    "items": {
+      "maximum": 100,
+      "minimum": 0,
+      "type": "number"
+    },
+    "maxItems": 4,
+    "minItems": 4,
+    "type": "array"
+  }
+]

changedInput schema / properties / headerTemplate / properties / color / description
```
Previous value: -"Hex colour."New value: +"Hex colour (#RRGGBB)."
```
removedInput schema / properties / headerTemplate / properties / color / pattern
```
Removed value: -"^#[0-9a-fA-F]{6}$"
```
removedInput schema / properties / headerTemplate / properties / color / type
```
Removed value: -"string"
```

changedInput schema / properties / headerTemplate / properties / left / description

Previous value: -"Placeholders: {page} {pages} {title} {date} (build-day wall clock, not creationDate)."New value: +"Placeholders: {page} {pages} {title} {date} (UTC date of creationDate when pinned, else of the build)."

changedInput schema / properties / headerTemplate / properties / right / description

Previous value: -"Placeholders: {page} {pages} {title} {date} (build-day wall clock, not creationDate)."New value: +"Placeholders: {page} {pages} {title} {date} (UTC date of creationDate when pinned, else of the build)."

changedInput schema / properties / includeDiagnostics / description

Previous value: -"Return the PDF/A diagnostics raised while building as `diagnostics[]` (possibly empty)."New value: +"Return the diagnostics raised while building (PDFA_*, PDFX_*, TYPOGRAPHY_*) as `diagnostics[]` (possibly empty)."

changedInput schema / properties / outputIntent / description

Previous value: -"Custom PDF/A OutputIntent: an RGB ICC profile + condition strings replacing the built-in sRGB intent (CMYK rejected)."New value: +"Custom OutputIntent (under pdfA or pdfx): an RGB, CMYK or Gray ICC profile + condition strings, replacing the built-in sRGB intent. The profile must be a real ICC file ('acsp' signature, consistent size — PRINT_ERROR otherwise); pdfx needs device class 'prtr'. Under a CMYK / Gray intent RGB content is mapped through a calibrated default space."

changedInput schema / properties / outputIntent / properties / iccProfileBase64 / description

Previous value: -"ICC profile bytes, base64 (RGB, ≤ 8 MiB)."New value: +"ICC profile bytes, base64 (RGB, CMYK or Gray; ≤ 8 MiB)."

changedInput schema / properties / print / properties / marks / oneOf

Previous value: -[
-  {
-    "type": "boolean"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "crop": {
-        "description": "Corner crop (trim) marks. Default true.",
-        "type": "boolean"
-      },
-      "length": {
-        "description": "Mark length in points. Default 14.",
-        "maximum": 100,
-        "minimum": 1,
-        "type": "number"
-      },
-      "offset": {
-        "description": "Gap between TrimBox and marks in points. Default 5.",
-        "maximum": 100,
-        "minimum": 0,
-        "type": "number"
-      },
-      "registration": {
-        "description": "Edge-midpoint registration targets. Default true.",
-        "type": "boolean"
-      },
-      "weight": {
-        "description": "Stroke width in points. Default 0.25.",
-        "maximum": 5,
-        "minimum": 0.05,
-        "type": "number"
-      }
-    },
-    "type": "object"
-  }
-]New value: +[
+  {
+    "type": "boolean"
+  },
+  {
+    "additionalProperties": false,
+    "properties": {
+      "colourBars": {
+        "anyOf": [
+          {
+            "type": "boolean"
+          },
+          {
+            "additionalProperties": false,
+            "properties": {
+              "size": {
+                "description": "Patch size in points. Default 12.",
+                "maximum": 72,
+                "minimum": 4,
+                "type": "number"
+              },
+              "tints": {
+                "description": "Add the four 50 % tint patches. Default true.",
+                "type": "boolean"
+              }
+            },
+            "type": "object"
+          }
+        ],
+        "description": "Colour control strip in the bleed (C M Y K solids + their 50 % tints): true for defaults. Off by default; needs a bleed of about 5 mm (14.17 pt) and is skipped when the strip would not fit."
+      },
+      "crop": {
+        "description": "Corner crop (trim) marks. Default true.",
+        "type": "boolean"
+      },
+      "length": {
+        "description": "Mark length in points. Default 14.",
+        "maximum": 100,
+        "minimum": 1,
+        "type": "number"
+      },
+      "offset": {
+        "description": "Gap between TrimBox and marks in points. Default 5.",
+        "maximum": 100,
+        "minimum": 0,
+        "type": "number"
+      },
+      "registration": {
+        "description": "Edge-midpoint registration targets. Default true.",
+        "type": "boolean"
+      },
+      "weight": {
+        "description": "Stroke width in points. Default 0.25.",
+        "maximum": 5,
+        "minimum": 0.05,
+        "type": "number"
+      }
+    },
+    "type": "object"
+  }
+]

changedInput schema / properties / strict / description

Previous value: -"Fail with PDF_A_COMPLIANCE_VIOLATION instead of producing a non-conformant PDF/A file (e.g. PDFA_NO_FONT_ENTRIES without embedFonts). Pair with embedFonts=true."New value: +"Fail instead of producing a file the engine warns about: a PDFA_* diagnostic → PDF_A_COMPLIANCE_VIOLATION (e.g. PDFA_NO_FONT_ENTRIES without embedFonts), a PDFX_* one → PDF_X_COMPLIANCE_VIOLATION, any other → DIAGNOSTIC_ESCALATED. Pair with embedFonts=true."

addedInput schema / properties / typography

Added value: +{
+  "additionalProperties": false,
+  "description": "Fine typography, all opt-in (omitted = unchanged bytes). kerning, fontFeatures and the 'fr' narrow space need embedFonts:true. No hyphenation dictionary is installed: use soft hyphens (U+00AD). See the typography prompt.",
+  "properties": {
+    "bindShortWords": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "additionalProperties": false,
+          "properties": {
+            "maxLength": {
+              "maximum": 3,
+              "minimum": 1,
+              "type": "integer"
+            },
+            "words": {
+              "items": {
+                "maxLength": 16,
+                "minLength": 1,
+                "type": "string"
+              },
+              "maxItems": 100,
+              "type": "array"
+            }
+          },
+          "type": "object"
+        }
+      ],
+      "description": "Never end a line on a short word: up to maxLength letters (default 1), or exactly the listed words."
+    },
+    "fontFeatures": {
+      "description": "OpenType features, later wins. tnum / lnum are no-ops on Noto Sans (TYPOGRAPHY_FEATURE_INEFFECTIVE).",
+      "items": {
+        "enum": [
+          "tnum",
+          "pnum",
+          "lnum",
+          "onum",
+          "zero",
+          "ordn",
+          "sups",
+          "subs",
+          "smcp",
+          "c2sc",
+          "case"
+        ],
+        "type": "string"
+      },
+      "maxItems": 11,
+      "type": "array",
+      "uniqueItems": true
+    },
+    "hyphenationLanguage": {
+      "description": "BCP 47 tag; no effect here (no hyphenation provider installed).",
+      "maxLength": 35,
+      "pattern": "^[A-Za-z]{2,3}(?:-[A-Za-z0-9]{2,8})*$",
+      "type": "string"
+    },
+    "keepHeadingsWithNext": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "additionalProperties": false,
+          "properties": {
+            "minLines": {
+              "maximum": 10,
+              "minimum": 1,
+              "type": "integer"
+            }
+          },
+          "type": "object"
+        }
+      ],
+      "description": "Never strand a heading at a page foot. true = { minLines: 2 }."
+    },
+    "kerning": {
+      "description": "Pair kerning (GPOS).",
+      "type": "boolean"
+    },
+    "metrics": {
+      "description": "Base-14 text: 'exact' uses the AFM widths (different wraps). Default 'approximate'.",
+      "enum": [
+        "approximate",
+        "exact"
+      ],
+      "type": "string"
+    },
+    "opticalMargins": {
+      "description": "Hang punctuation into the margin of align:'justify' text.",
+      "type": "boolean"
+    },
+    "orphans": {
+      "description": "Min lines left at a page foot (default 2; needs splitParagraphs).",
+      "maximum": 10,
+      "minimum": 1,
+      "type": "integer"
+    },
+    "punctuationSpacing": {
+      "anyOf": [
+        {
+          "enum": [
+            "fr",
+            "fr-CA"
+          ],
+          "type": "string"
+        },
+        {
+          "items": {
+            "additionalProperties": false,
+            "properties": {
+              "char": {
+                "maxLength": 2,
+                "minLength": 1,
+                "type": "string"
+              },
+              "side": {
+                "enum": [
+                  "before",
+                  "after"
+                ],
+                "type": "string"
+              },
+              "space": {
+                "description": "U+00A0 / U+202F (narrow needs embedFonts).",
+                "enum": [
+                  "nbsp",
+                  "narrow"
+                ],
+                "type": "string"
+              }
+            },
+            "required": [
+              "char",
+              "side",
+              "space"
+            ],
+            "type": "object"
+          },
+          "maxItems": 32,
+          "type": "array"
+        }
+      ],
+      "description": "No-break spaces next to punctuation (existing spaces only). 'fr': narrow before ; ! ?, no-break before ':' and inside « ». 'fr-CA': ':' and « » only. Or explicit rules."
+    },
+    "splitParagraphs": {
+      "description": "Paragraphs may break across pages at a line boundary (default: atomic).",
+      "type": "boolean"
+    },
+    "unitBinding": {
+      "anyOf": [
+        {
+          "type": "boolean"
+        },
+        {
+          "additionalProperties": false,
+          "properties": {
+            "units": {
+              "items": {
+                "maxLength": 16,
+                "minLength": 1,
+                "type": "string"
+              },
+              "maxItems": 100,
+              "type": "array"
+            }
+          },
+          "type": "object"
+        }
+      ],
+      "description": "No-break space between a number and its unit ('150 €', '12 kg'); units replaces the built-in list."
+    },
+    "widows": {
+      "description": "Min lines carried over (default 2; needs splitParagraphs).",
+      "maximum": 10,
+      "minimum": 1,
+      "type": "integer"
+    }
+  },
+  "type": "object"
+}

changedOutput schema / properties / diagnostics / description

Previous value: -"PDF/A diagnostics (when includeDiagnostics=true)."New value: +"Engine diagnostics (when includeDiagnostics=true)."

AddedAug 24, 2026
Removedv1.6.0Jul 22, 2026

Changed2 schema fields changedv1.2.0Jun 24, 2026

addedOutput schema / description

Added value: +"Structured result of a PDF-producing tool. In base64 mode the PDF bytes are delivered out-of-band as an embedded `resource` content block (data: URI), NOT duplicated here, to keep responses token-frugal. In file mode `filePath` is the sandboxed absolute path."

removedOutput schema / properties / base64

Removed value: -{
-  "description": "Base64-encoded PDF bytes (when mode='base64').",
-  "type": "string"
-}

First observedv1.1.0Jun 20, 2026

TDQS

A4.8/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only say readOnly=false, idempotent=true, destructive=false, so the description carries real weight: it discloses that signerName/reason/location/contactInfo/signingTime are frozen into /Sig at placeholder time and sign_pdf cannot rewrite them later, and that the unsigned output is not yet conformant PDF/A because /Contents is empty. These are non-obvious behavioral consequences not derivable from the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The critical framing (what it is, that it is optional, that sign_pdf auto-injects) comes first, and the rest is a tight enumeration of reasons to use it. Sentences are dense and information-packed for a 29-parameter tool, though the parenthetical lists make it slightly harder to scan than an ideal definition.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, the description need not document return values, and with annotations covering the safety profile it mainly needs to convey the placeholder-specific semantics — freezing, nonconformance, and sizing. It does all of that, plus points to shared options, so an agent has everything needed to decide whether and how to call it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is already 100%, so the baseline is 3, but the description adds genuine selection guidance beyond the schema: which situations justify placeholderBytes (large RSA keys, long chains), what reserveTimestamp is for, how pageIndex pins the widget, and the PAdES role of subFilter. It also forward-references cross-cutting options (PDF/A, print, metadata, creationDate) as shared document-tool conventions. It does not attempt to restate all 29 parameters, which is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and artifact: creates a new PDF carrying an unsigned /Sig placeholder explicitly intended for a LATER sign_pdf call. This clearly separates it from sign_pdf and from generate_basic_pdf, so the agent knows this is a preparatory step, not the signing step.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly declares itself OPTIONAL and names the alternative that makes it unnecessary ('sign_pdf auto-injects one'). It then enumerates the concrete reasons to use it anyway: sizing placeholderBytes for >4096-bit keys, reserveTimestamp for an RFC 3161 token, pinning pageIndex, choosing the PAdES subFilter, or shipping the placeholder separately. Both when-to-use and when-not-to-use are covered.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.