Claude Desktop Signbee MCP Setup: Send Your First E-Sign Document (2026)

Why AI Agents Need a Native Signing Tool in Claude Desktop

Autonomous chat assistants excel at drafting legal agreements. Within seconds, Claude 3.5 Sonnet can compose a bulletproof Mutual Non-Disclosure Agreement (NDA), an intellectual property assignment, or a freelance statement of work. Yet historically, that workflow hit an abrupt brick wall: the user had to copy the text, paste it into a word processor, export a PDF, upload it to a legacy e-signature portal, manually drag signature boxes across canvas coordinates, and type recipient emails into separate form fields.

The Model Context Protocol (MCP), open-sourced by Anthropic, fundamentally transforms this interaction. By exposing structured execution tools directly to the model over local standard input/output (stdio), Claude can bridge the chasm between document composition and legal execution. With the Signbee MCP server (signbee-mcp), you can simply tell Claude: "Draft an NDA between Alice and Bob, and send it for signature."

Claude drafts the agreement terms in clean GitHub Flavored Markdown, maps the signatories to typed parameters, and dispatches the signing ceremony in a single autonomous turn. No third-party tabs, no manual PDF preparation, and no seat licenses required.

Step 1: Locating and Editing claude_desktop_config.json

Claude Desktop discovers local tools through its centralized configuration file, claude_desktop_config.json. Depending on your operating system, this JSON configuration lives in your local application support directory:

You can open the directory directly from Claude Desktop by clicking Claude in the menu bar, selectingSettings (or pressing Cmd + , / Ctrl + ,), navigating to the Developer tab, and clicking Edit Config.

Option A: Zero-Config OTP Mode (No API Key Required)

Signbee adheres strictly to a zero-friction philosophy: you should never have to create an account, register a credit card, or generate API keys just to evaluate whether a tool functions. In zero-config mode, the MCP server runs with zero environment variables. When a document is dispatched, Signbee routes an email verification code directly to your sender inbox:

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

Option B: Production Mode with SIGNBEE_API_KEY

When deploying Signbee in automated workflows where you want instant, single-turn dispatches without pausing for an interactive email OTP verification code, add your API key into the env block. You can generate a free API key from the Signbee Dashboard:

{
  "mcpServers": {
    "signbee": {
      "command": "npx",
      "args": [
        "-y",
        "signbee-mcp"
      ],
      "env": {
        "SIGNBEE_API_KEY": "sb_live_your_api_key_here"
      }
    }
  }
}

Step 2: Verifying MCP Tool Registration in Claude

Once Claude Desktop restarts, look at the bottom-right corner of the chat prompt input area. You will notice a small hammer icon. Clicking this icon reveals all active Model Context Protocol tools currently connected to the Claude runtime.

You should see the signbee server active, exposing exactly two dedicated tools:

• send_document — Takes a dynamic Markdown document string and an array of signer objects (name and email), renders the contract, and dispatches signature requests.
• send_document_pdf — Dispatches pre-existing, publicly accessible PDF URLs directly to signers without converting from Markdown.

Notice how clean this tool surface is. While enterprise e-signature SDK wrappers inject over 2,500 tokens of bloated JSON schema into Claude's context window (detailing envelope states, manual tab placement, coordinate arrays, and branding options), Signbee MCP consumes just ~340 tokens total. This lightweight footprint prevents context dilution and ensures Claude 3.5 Sonnet selects the correct tool parameters with zero hallucination.

Authentication Comparison: Email OTP vs SIGNBEE_API_KEY

Signbee is built to accommodate both rapid prototyping and automated commercial workflows. Understanding how authentication functions helps you choose the right configuration for your setup:

In OTP mode, when Claude triggers send_document, Signbee recognizes that no authorization token was passed in the headers. The API creates a pending dispatch state and sends an immediate 6-digit numeric OTP to the first party listed as the sender. Claude detects this requirement from the tool response and prints:

Once you type the code in chat, Claude passes it back to the tool, and the agreement is delivered immediately to all signing parties.

Step 3: Sending Your First Two-Party Agreement (Interactive Ceremony)

Now that the MCP server is connected, test a complete real-world scenario: generating and dispatching a binding two-party Mutual Non-Disclosure Agreement (NDA).

In a fresh Claude Desktop conversation window, paste the following instruction:

Claude will analyze your request, formulate a well-structured legal agreement using GitHub Flavored Markdown, and invoke the send_document tool. Here is the exact JSON structure that Claude constructs under the hood:

{
  "document": "# Mutual Non-Disclosure Agreement\n\nThis Mutual Non-Disclosure Agreement ("Agreement") is entered into on September 5, 2026, by and between:\n\n1. **Acme Software Ltd**, represented by Alice Smith (alice@example.com) ("Party A"), and\n2. **Jones Consulting**, represented by Bob Jones (bob@example.com) ("Party B").\n\n### 1. Definition of Confidential Information\n"Confidential Information" refers to all proprietary data, code repositories, system architectures, customer lists, and commercial trade secrets disclosed by either party...\n\n### 2. Obligations of Non-Disclosure\nEach party agrees to hold all Confidential Information in strict confidence and prevent unauthorized disclosure using at least reasonable care for a period of two (2) years from disclosure...\n\n### 3. Exclusions\nThis Agreement imposes no obligation upon information that is publicly known, already in possession of the recipient prior to disclosure, or independently developed...\n\n### 4. Governing Law and Jurisdiction\nThis Agreement shall be construed in accordance with and governed by the laws of England and Wales.\n\n---\n\n### Signatures\nBy signing below, both parties confirm their agreement to the terms above.",
  "parties": [
    {
      "name": "Alice Smith",
      "email": "alice@example.com"
    },
    {
      "name": "Bob Jones",
      "email": "bob@example.com"
    }
  ]
}

The Signbee MCP server validates the payload, transmits the document to the Signbee backend over TLS 1.3, compiles the markdown into a standardized PDF layout, and returns an execution receipt directly to Claude:

{
  "success": true,
  "document_id": "doc_9f83a7c1e4d28b",
  "status": "pending_signatures",
  "signers": [
    {
      "name": "Alice Smith",
      "email": "alice@example.com",
      "signing_url": "https://signb.ee/sign/doc_9f83a7c1e4d28b?signer=s_01"
    },
    {
      "name": "Bob Jones",
      "email": "bob@example.com",
      "signing_url": "https://signb.ee/sign/doc_9f83a7c1e4d28b?signer=s_02"
    }
  ],
  "message": "Agreement dispatched successfully. Invitation emails delivered to all parties."
}

Claude summarizes the output in natural language, confirming that the NDA has been dispatched and providing direct status references for both Alice and Bob.

Tool Selection: send_document vs send_document_pdf

The Signbee MCP server provides two distinct tools. Knowing when to direct Claude toward each tool ensures optimal contract fidelity and token efficiency:

For 95% of generative AI workflows in Claude Desktop, send_document is the optimal choice. It eliminates intermediate file storage, cloud bucket permissions, and format conversion headaches. Claude authors the terms in plain markdown, and Signbee turns it into a pixel-perfect, certified legal document.

What Signers Experience: Zero-Friction Web Signing Ceremony

A major vulnerability of legacy enterprise e-signature platforms is signer friction. When signers receive an invitation, they are frequently confronted with forced account registration, password creation, multi-step identity profiling, and aggressive upsell banners.

Signbee eliminates every barrier for your human counterpart:

1. Clean Email Invitation: Delivered via Amazon Simple Email Service (SES) with authenticated SPF, DKIM, and DMARC alignment, ensuring the invitation arrives in the recipient's primary inbox.
2. One-Click Responsive Web Viewer: Clicking the secure review link opens a responsive browser window formatted cleanly for both mobile and desktop screens.
3. Zero Account Requirement: The recipient never creates an account or downloads an application. The identity is bound to their verified email session.
4. Draw or Type Execution: Signers can draw their legal signature with a trackpad, mouse, or touchscreen, or select an auto-rendered signature typeface.

The Cryptographic SHA-256 Audit Certificate

Once both Alice and Bob complete the web signing ceremony, what happens to the executed agreement? Signbee seals the document using an immutable, cryptographic audit trail.

Signbee compiles the rendered markdown, embeds the high-resolution vector signatures of both parties, and appends a dedicated, tamper-evident Certificate of Completion as the final page of the PDF. This certificate captures:

Both parties automatically receive an email containing the completed PDF. Anyone can independently verify the authenticity of the document by computing the SHA-256 hash using standard command-line tools:

# Compute the SHA-256 checksum of your executed agreement
shasum -a 256 mutual_nda_signed.pdf

# Output matches the hash printed on the Certificate of Completion:
# 8f4a3e7b91d20c5f6a4e8b7c3d2e1f0a9b8c7d6e5f4a3b2c1d0e9f8a7b6c5d4e  mutual_nda_signed.pdf

To learn more about the underlying cryptographic mechanics, read our in-depth architecture post on How the SHA-256 Signing Certificate Works.

Why MCP Does Not Take webhook_url (And How to Handle Async Events)

Developers frequently ask: "Can I pass a webhook_url to the Signbee MCP tool so my local Claude session is notified when the document is signed?"

The short answer is no. The Signbee MCP server intentionally does not accept a webhook_url parameter. Understanding why is crucial to architecting production agent systems:

If your system requires automated, asynchronous event notification when a contract is executed (such as automatically provisioning software access, issuing an invoice, or updating an external CRM), you should invoke Signbee via the direct REST API:

curl -X POST https://signb.ee/api/v1/send \
  -H "Authorization: Bearer sb_live_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "document": "# Enterprise Service Agreement\n\n...",
    "parties": [
      { "name": "Alice Smith", "email": "alice@example.com" },
      { "name": "Bob Jones", "email": "bob@example.com" }
    ],
    "webhook_url": "https://api.yourdomain.com/webhooks/signbee"
  }'

When both parties complete signing, Signbee delivers an authenticated document.signed webhook with HMAC SHA-256 signatures to your server. To explore how to configure and verify webhook payloads, check out:

• Agent Document Signing Webhooks: Get document.signed Without Polling — Comprehensive guide to HMAC verification and webhook event payloads.
• Agent Document Signing: Skills vs MCP vs API — When to Use Each — Detailed architectural comparison across token costs, latency, and system execution boundaries.
• Signbee API Documentation — Complete REST API reference and schema definitions.
• Signbee MCP GitHub Repository — Source code, Dockerfile, and open-source issue tracker.

Troubleshooting Common Claude Desktop Setup Pitfalls

If the hammer icon does not appear or tool dispatches fail, verify these four common environment configurations:

Frequently Asked Questions