How to Send Documents for Signature with Claude

You can now send documents for signature with Claude — or with any AI agent that speaks the open MCP standard. Type "Send the liability release to Anna — anna@example.com" into a chat, and your assistant creates the document from your AddSign template, emails the signing link, tracks who has viewed and signed, nudges slow signers, and hands you the signed PDF when it's done. No tab-switching, no copy-pasting email addresses into a web form.

This guide covers the three ways to connect an AI agent to AddSign, what the agent can do once connected, and — just as important for anything touching signatures — what it deliberately cannot do.

What "Agent-Ready" Means

AddSign runs an e-signature MCP server — MCP being the Model Context Protocol, the open standard AI assistants use to work with outside tools. Anthropic's Claude speaks it natively, and a growing list of other agents and IDEs (Cursor, Windsurf, and others) do too. Connect once, and your assistant gains a small, carefully scoped set of document tools tied to your AddSign account — and only yours.

There are three ways to connect, depending on where your AI lives.

Path 1: claude.ai — Connect in About a Minute, No API Key

If you use Claude in the browser or the mobile app, this is the easiest path. It uses secure OAuth — you log in and approve, and no keys or passwords are ever copied anywhere.

1. In Claude, open Settings → Connectors and choose Add custom connector.
2. Paste the connector URL: https://addsign.io/api/mcp
3. Claude redirects you to AddSign to log in (or sign up free).
4. A consent screen shows you exactly what the connection can and cannot do — approve it, and you're done.

From that point, any chat can use your AddSign account: "What templates do I have?" or "Send the service agreement to my new client." Disconnecting the connector in Claude's settings instantly revokes all access.

One note: custom connectors are a feature of paid Claude plans. If you're on the free Claude tier, use the API-key paths below instead.

Path 2: Claude Desktop — One-Click Extension

For the Claude Desktop app, AddSign ships as a desktop extension — a single file, no config editing.

1. Download the extension: addsign.io/downloads/addsign.mcpb
2. Open it with Claude Desktop (double-click or drag it into the app) and click Install.
3. When prompted, paste an AddSign API key. Create one in about 10 seconds at Settings → API in your AddSign dashboard.

The key is stored in your operating system's keychain — not in a text file, not in the chat. You can name keys, scope them, and revoke any of them from the dashboard at any time.

Path 3: Any MCP Agent — the addsign-mcp Package

For Claude Code, Cursor, Windsurf, custom agents, or anything else that runs MCP servers, AddSign publishes an npm package, listed in the official MCP Registry as io.github.rmindgh/addsign-mcp.

The quickest setup, using Claude Code as the example:

claude mcp add addsign \
  --env ADDSIGN_API_KEY=your_key_here \
  -- npx -y addsign-mcp

Or the generic JSON config most MCP clients accept:

{
  "mcpServers": {
    "addsign": {
      "command": "npx",
      "args": ["-y", "addsign-mcp"],
      "env": { "ADDSIGN_API_KEY": "your_key_here" }
    }
  }
}

Your AddSign dashboard has ready-to-copy setup instructions for each client under Settings → API → Connect your agent — pick your tool from the dropdown and copy.

What Your Agent Can Do

Once connected, your assistant has six capabilities, all scoped to your account:

• List your templates — including the signer roles each one expects
• Send a document from a template — to one signer or several, in parallel or in signing order
• Check status — who viewed, who signed, who declined (and why), with timestamps
• List your documents — filterable by status, e.g. "show me everything still waiting"
• Remind pending signers — politely throttled server-side so nobody gets spammed
• Fetch the signed PDF — a short-lived download link plus the document's SHA-256 hash from the audit trail, so you can verify the file hasn't been altered since it was signed

Some real prompts that work as-is:

"Send my Liability Release template to Mike Carter — mike@example.com."

"Did anyone sign the consulting agreement yet?"

"Remind everyone who hasn't signed the lease renewal."

"Get me the signed PDF for the Johnson contract."

Not sure about a send? Ask the agent to do a dry run first — it validates everything (template, recipients, plan limits) and reports exactly what would go out, without sending anything.

What It Deliberately Cannot Do

Signatures are serious, so the connection is engineered to be boring. Five guardrails are built in:

1. It never guesses an email address. The agent is instructed to use exactly the addresses you give it and to restate the full recipient list before sending. Vague request, no send.
2. It cannot cancel, void, or delete anything. There is no destructive tool in the set — a mis-send is corrected by you, from your dashboard, in one click.
3. You get an email for every document your agent sends. Every agent-initiated send triggers an owner notification with a View/Cancel link — you always know what went out, even if you weren't watching the chat.
4. Every action is attributed in the audit trail. Documents sent by an agent are recorded as such, alongside the same tamper-evident trail (including the SHA-256 document hash) that every AddSign document gets.
5. Access dies instantly when you disconnect. Removing the connector or revoking the API key kills the agent's access on the spot — nothing lingers.

And to be precise about roles: the agent sends documents — humans sign them. Your signers receive a normal AddSign email, review the document, and sign it themselves. Electronic signatures collected this way are generally legally binding under the ESIGN Act and UETA, the same as any other AddSign document.

Your Signers Don't Need Anything

Nothing changes on the receiving end. Signers get an email, click the link, and sign from their phone or computer in a couple of minutes — no account, no app, no idea (unless you tell them) that an AI handled the paperwork. For businesses that send the same documents over and over — think real estate agents buried in listing paperwork, property managers at renewal season, or brokers sending carrier agreements — that's the whole point: the repetitive half of signature work disappears into a sentence.

Frequently Asked Questions

Can Claude really send documents for signature?

Yes. With AddSign connected, Claude can create a document from one of your templates and email it to signers — then track it, remind signers, and fetch the signed PDF. It works on claude.ai, in the Claude Desktop app, and in any MCP-capable agent.

Is it safe to let an AI near legal documents?

The connection is designed around that exact worry. The agent can only send, track, remind, and download — it cannot cancel or delete anything, it must restate recipients before sending, you receive an email for every send it makes, and every action lands in the audit trail. You can revoke access instantly at any time.

Do I need an API key?

On claude.ai — no. The custom connector uses OAuth: you log into AddSign and approve, and no key exists at all. The Claude Desktop extension and CLI/agent setups use an API key, which you can create and revoke in seconds from your dashboard.

Does this work with AI agents other than Claude?

Yes. AddSign's integration is built on MCP, an open standard. Any agent, IDE, or assistant that supports MCP servers can connect using the addsign-mcp package and an API key.

What does it cost?

Agent access is included on every AddSign plan — including the free plan. API keys and the MCP connection aren't paywalled; your normal plan limits (like monthly document count) simply apply to agent sends the same way they apply to sends from the dashboard.

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This post is for informational purposes only and does not constitute legal advice. Electronic signature laws vary by state and document type. Consult a legal professional to determine whether electronic signatures are appropriate for your specific use case.

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