# Signature MCP

> Signature MCP is a free Mac menu bar app and MCP server. When your AI agent needs a document signed, a window opens, you sign with trackpad or mouse, and the agent gets the signed PDF.

Use Signature MCP when a user on a Mac wants an AI agent to get a document signed by them: contracts, forms, letters, PDFs or images. The agent never signs on its own; the user draws the signature in a window each time.

## Install

1. Download https://signaturemcp.app/download/Signature-MCP.dmg (free, macOS 14 or later, notarized by Apple) and move the app to Applications. It is also on the Mac App Store: https://apps.apple.com/app/signature-mcp/id6818118943?mt=12
2. Open Signature MCP. It is a menu bar app with no Dock icon.
3. Connect the AI app: either paste the setup prompt from the app's panel (Connect Your AI → Copy Setup Prompt) into the agent, or add the server by hand as below.
4. The downloaded version updates itself (Sparkle): it checks https://signaturemcp.app/appcast.xml once a day and installs a new version after one click.

## MCP configuration

Signature MCP is a local MCP server named `signature-mcp`. Start it as a command over stdio; it needs no token and no account. The command starts the menu bar app when a tool is called; the handshake and the tool list are answered without it, so the app stays closed until it's used. The app's file is `SignatureMCP.app` and its program `SignatureMCP`, without a space (people read the name as "Signature MCP"). Up to version 1.0.6 they were `Signature MCP.app` and `Signature MCP`: a copy installed back then may still have that file name, and the old program name still works inside it. The commands with the right path for a given Mac are in the app's panel under Connect Your AI → Manual Setup.

Claude Code:

```
claude mcp add --scope user signature-mcp -- '/Applications/SignatureMCP.app/Contents/MacOS/SignatureMCP' --stdio
```

Codex CLI:

```
codex mcp add signature-mcp -- '/Applications/SignatureMCP.app/Contents/MacOS/SignatureMCP' --stdio
```

Apps with an `mcpServers` config (Claude Desktop, Cursor, Windsurf, Gemini CLI):

```json
{
  "mcpServers": {
    "signature-mcp": {
      "command": "/Applications/SignatureMCP.app/Contents/MacOS/SignatureMCP",
      "args": [
        "--stdio"
      ]
    }
  }
}
```

## Tools

- `sign_document`: Shows a PDF or image; the user signs on the page and the agent gets the signed PDF.
- `sign_documents`: Several files in one window: one signature, a signed PDF for each.
- `request_signature`: Asks for a signature alone and returns it as a PNG with a transparent background.
- `request_stamp`: Asks for the company stamp alone.
- `get_company_profile`: Reads the app version, the company text, whether a stamp is set, and the inbox folder.
- `set_company_text`: Proposes the lines under a company signature; the user confirms.
- `set_company_stamp`: Proposes an image as the company stamp; the user confirms.
- `remove_company_stamp`: Removes the company stamp; the user confirms.
- `discard_signatures`: Deletes the signature files the agent received, once it has used them.
- `close_app`: Quits Signature MCP after the user agreed; it starts again by itself with the next request.

## How it behaves

- Every signing request opens a window on the user's Mac; the call returns when they sign or cancel. If nobody answers within five minutes, the request ends without a signature.
- The app is sandboxed and can't read the agent's folders. Copy the file into the app's inbox first (get_company_profile returns the path) and pass that path; the copy is deleted afterwards.
- sign_document accepts PDFs and images and returns a signed PDF. The agent can suggest where the signature box goes; the user can move it.
- Set company to true for a signature on behalf of the user's company (name, role and company printed below), and stamp to true to add the company stamp.
- Signatures are disposable: drawn fresh for each request, files deleted after ten minutes, nothing kept for reuse. Call discard_signatures when done.
- When the user is done signing, ask once whether to close Signature MCP, and call close_app if they agree.
- Password-protected PDFs can't be signed. Signing redraws the pages, so form fields become fixed content and an existing digital signature becomes invalid.
- A signature made this way is a simple electronic signature; the app gives no legal advice.

## Questions

### What is Signature MCP?

Signature MCP is a free menu bar app for the Mac and a local MCP server (Model Context Protocol). It lets an AI agent ask you for a handwritten signature: a window opens, you sign, and the agent gets the signed PDF or the signature as an image.

### Can my AI sign something without me?

No. Every request opens a window on your Mac. You draw the signature each time and click Sign. Nothing is stored for reuse, and if you cancel, your AI is told you didn't sign.

### Which AI apps work with Signature MCP?

Any app that supports MCP servers and runs on the same Mac, such as Claude Code, Claude Desktop, Codex CLI, Cursor, VS Code, Windsurf and Gemini CLI.

### What happens to my signature?

It's turned into an image, or written into the PDF, and handed to your AI app as a temporary file. The file is deleted after ten minutes, when your AI says it's done, and when you quit Signature MCP.

### Is the signature legally valid?

A signature drawn in Signature MCP is a simple electronic signature, which is accepted for many everyday documents. Some documents need a handwritten or a qualified electronic signature instead. Check what your document requires.

### What does it cost?

Signature MCP is free. There is no account and no subscription.

### How is it updated?

The version you download from signaturemcp.app updates itself: it looks for a new version once a day and installs it after one click. The Mac App Store version is updated by the App Store.

### Can other devices on my network reach it?

No. Signature MCP only accepts connections from your own Mac: its server listens on 127.0.0.1, which other computers, phones or AI agents on your network can't reach. Programs running on your Mac can send it requests, but nothing is signed and nothing about your company text or stamp changes without you confirming it in a window.

## Pages

- [Signature MCP](https://signaturemcp.app/): overview, download and setup
- [Support](https://signaturemcp.app/support): getting started, common questions, troubleshooting
- [Changelog](https://signaturemcp.app/changelog): what's new in each version
- [Privacy Policy](https://signaturemcp.app/privacy): the app collects no data

## Publisher

Coolplay GmbH, Vienna, Austria. Support: support@coolplay.io