toolbox-mcp

An MCP server that gives AI agents 35 fast, local, privacy-first tools. PDF text extraction and editing, image processing, exact math, QR codes, crypto, timezone conversion, regex, diff, JSON and CSV, and more. Everything runs on your own machine over stdio. No network calls, nothing leaves your computer.

Inspired by the browser toolbox at footrue.com, reimplemented in Node so agents like Claude can call the same kind of tools directly.

Why

Agents reason well but keep getting deterministic tasks subtly wrong: arithmetic, timezone math, regex, reading a PDF, generating a QR code, hashing a password. This server hands those tasks to real, tested functions, so the agent gets the exact right answer every time, without burning tokens and without sending your data anywhere.

Tools

PDF

Tool	What it does
`pdf_extract_text`	Pull the readable text out of a PDF so an agent can read it
`pdf_merge`	Merge several PDFs into one
`pdf_split`	Extract a page range into a new PDF
`pdf_rotate`	Rotate all pages by 90 / 180 / 270
`images_to_pdf`	Combine PNG/JPG images into a PDF, one per page
`pdf_info`	Page count, title, author, file size

Image

Tool	What it does
`image_convert`	Convert between png, jpeg, webp, avif, gif, tiff
`image_resize`	Resize by width and/or height with fit control
`image_compress`	Shrink file size at a chosen quality
`image_rotate`	Rotate by any angle
`image_grayscale`	Convert to black and white
`image_crop`	Crop a rectangular region
`image_watermark`	Overlay a text watermark
`image_info`	Format, dimensions, channels, file size

Compute (the things LLMs get wrong)

Tool	What it does
`calculate`	Evaluate a math expression exactly, including unit conversions
`timezone_convert`	Convert a date-time between IANA timezones
`regex_extract`	Apply a regex and return every match exactly
`diff_text`	Precise line-by-line diff of two texts
`qr_generate`	Generate a QR code PNG from text or a URL

Crypto and security

Tool	What it does
`hash_text`	md5 / sha1 / sha256 / sha384 / sha512 of text
`hmac_sign`	HMAC signature with a secret key
`bcrypt_hash` / `bcrypt_verify`	Hash and check passwords with bcrypt
`generate_uuid`	One or more random v4 UUIDs
`jwt_decode`	Decode a JWT header and payload (no signature check)

Data and text

Tool	What it does
`format_json`	Validate and pretty-print or minify JSON
`csv_to_json`	CSV into a JSON array of objects
`convert_color`	Hex color into RGB and HSL
`base64_encode` / `base64_decode`	Base64 both ways
`url_encode` / `url_decode`	Percent-encode and decode
`slugify`	Text into a clean URL slug
`change_case`	upper, lower, title, sentence, camel, snake, kebab, constant
`text_stats`	Word, character, sentence, line counts and reading time

PDF and image tools read and write files by path, so the agent can hand you a document and get a processed file back. Everything runs on your own machine.

Setup

toolbox-mcp is a standard stdio MCP server, so it works in any MCP client. The easiest way is npx, which downloads and runs it with no install or build step. Just add one of the configs below.

Claude Desktop / Cursor

Edit claude_desktop_config.json (Claude) or the MCP settings (Cursor):

{
  "mcpServers": {
    "toolbox": {
      "command": "npx",
      "args": ["-y", "toolbox-mcp"]
    }
  }
}

VS Code (Copilot agent mode)

Create .vscode/mcp.json in your workspace, or run MCP: Open User Configuration from the Command Palette. Note that VS Code uses the servers key:

{
  "servers": {
    "toolbox": {
      "command": "npx",
      "args": ["-y", "toolbox-mcp"]
    }
  }
}

Google Antigravity

Open Settings > Customizations > Open MCP Config (this edits ~/.gemini/config/mcp_config.json), then add:

{
  "mcpServers": {
    "toolbox": {
      "command": "npx",
      "args": ["-y", "toolbox-mcp"]
    }
  }
}

Save and hit refresh in the Installed MCP Servers section.

After configuring, restart or refresh the client and the tools appear automatically. Then just ask, for example, "read this PDF", "convert this image to webp", or "what is 90 km/h in m/s", and the agent will call the tool.

Run from source

To hack on it locally instead of using npx:

git clone https://github.com/medoxisto/toolbox-mcp
cd toolbox-mcp
npm install
npm run build   # or: npm run dev

Then point your client at node /absolute/path/to/toolbox-mcp/dist/index.js.

Privacy

Everything runs locally over stdio. There are no network requests and no telemetry. The compute, data and crypto tools are pure functions; the PDF and image tools read and write only the file paths you give them. Your data never leaves your machine.

Contributing

The toolbox is easy to extend: each tool is a small object with a name, description, a zod schema, and a handler that returns a string. See src/tools. PRs that add useful, deterministic, network-free tools are welcome.

License

MIT. See LICENSE.