PDF Form Proof MCP server

pdf-form-proof

Fill a fillable PDF form, then prove every value actually shows on the page.

mcp-name: io.github.EssenceAlignment/pdf-form-proof

A PDF can hold a value in its data while the page a person sees, prints, or uploads shows nothing, or shows it cut off. Most form tools stop at "the field was set." This one keeps going: it renders the page, reads it back with OCR (optical character recognition, software that reads text from an image), and compares that with the text stored in the file. Each value comes back VISIBLE, INVISIBLE, RENDER-ONLY, or MISSING.

It works as an MCP server (MCP, the Model Context Protocol, is the plug-in standard that lets AI apps such as Claude call outside tools), as a Claude plugin, as a Gemini CLI extension, and as plain command-line tools.

What it does

Every tool carries MCP annotations: readOnlyHint and destructiveHint are set on all four.

Who it is for

Anyone who fills the same official PDFs again and again: small nonprofits and community organizations (vendor forms such as the IRS W-9, grant and funder forms, program intake and consent forms), operations staff, and builders who want an AI assistant to fill forms without hiding a partial or invisible fill.

Install

You need Python 3.10 or newer and uv (https://docs.astral.sh/uv/). The verify tool also needs two free programs:

• macOS: brew install poppler tesseract
• Debian or Ubuntu: sudo apt install poppler-utils tesseract-ocr

Claude Desktop (MCP server)

Add this to claudedesktopconfig.json:

{
  "mcpServers": {
    "pdf-form-proof": {
      "command": "uvx",
      "args": ["pdf-form-proof"]
    }
  }
}

Or install the .mcpb file from the latest GitHub release: double-click it, or use Settings > Extensions > Advanced settings > Install Extension.

Claude Code (plugin)

claude plugin marketplace add EssenceAlignment/pdf-form-proof
claude plugin install pdf-form-proof@pdf-form-proof

Gemini CLI (extension)

gemini extensions install https://github.com/EssenceAlignment/pdf-form-proof

Command line

uvx --from pdf-form-proof pdf-form-inspect form.pdf
uvx --from pdf-form-proof pdf-form-fill form.pdf filled.pdf values.json
uvx --from pdf-form-proof pdf-form-verify filled.pdf --require "Sample Community Food Bank"

values.json maps exact field names (from pdf-form-inspect) to values:

{
  "topmostSubform[0].Page1[0].f1_01[0]": "Sample Community Food Bank",
  "topmostSubform[0].Page1[0].Boxes3a-b_ReadOrder[0].c1_1[0]": "/1"
}

Text fields take a string. A checkbox or radio takes one of its on-state values (shown by inspect, for example "/1" or "/Yes"), or an empty string to clear it.

Exit codes: 0 success; 1 a finding (verify found a value that is not visible, or a fill could not be read back); 2 refused (unknown field names, a missing file, an existing output, or a tool such as tesseract failed).

Example

Shortened. The full README is on GitHub.