How to set up an MCP email assistant with PureBox

The Model Context Protocol (MCP) is rapidly becoming the industry standard for connecting AI clients—such as Claude Desktop, Cursor, ChatGPT, and Windsurf—to external systems. Rather than granting general AI models raw credentials to your Gmail account, PureBox provides an official Hosted MCP Server that exposes bounded, safe tools for mailbox inspection and triage.

This guide walks through setting up PureBox as an MCP server, explaining the security architecture, available tools, and conversational workflows.

Publisher disclosure: PureBox publishes this technical guide and operates the MCP server described. This guide reflects the production MCP interface verified on 2026-10-22.

Why use PureBox MCP instead of raw mailbox access?

Connecting a general-purpose AI assistant directly to an email API presents significant hazards:

1. Context window overflow: Large language models cannot load thousands of emails into their prompt context without hitting token limits or losing critical details.
2. Hallucination risks: Without verified sender heuristics, a raw model might hallucinate that an urgent flight reservation or legal confirmation is disposable spam.
3. Unbounded write operations: Granting an autonomous agent direct write or delete permissions exposes your mailbox to accidental mass deletion without an undo trail.

PureBox acts as an intelligent protective layer between your assistant and Gmail:

• Server-owned apply plans: Assistants cannot construct arbitrary deletion calls. Any proposed cleanup action is compiled into a bounded, immutable apply plan.
• You approve what moves: Guardrails require explicit human confirmation before changes reach your Gmail account.
• Token isolation: Your assistant never receives Google OAuth tokens or mailbox passwords.

Architecture and authentication flow

PureBox implements a decoupled, two-layer authentication model:

• Layer 1 (Assistant to PureBox): Your MCP client discovers https://api.purebox.ai/.well-known/oauth-protected-resource and presents a resource-bound OAuth 2.1 bearer token from the MCP authorization server, which PureBox verifies against its JWKS.
• Layer 2 (PureBox to Gmail): PureBox uses your stored Google OAuth credentials (gmail.modify) to interact with Gmail.

If your Gmail token expires, PureBox returns a structured needs_user_action issue envelope with a deep link to re-authenticate, ensuring the assistant never encounters ambiguous transport crashes.

┌─────────────────────┐
│   AI Assistant      │  (Claude / Cursor / ChatGPT)
└──────────┬──────────┘
           │ OAuth 2.1 Bearer Token
           ▼
┌─────────────────────┐
│  PureBox MCP Server │  https://api.purebox.ai/mcp
│  • Immutable Plans  │
│  • Canonical Tracks │
└──────────┬──────────┘
           │ Managed Google OAuth (gmail.modify)
           ▼
┌─────────────────────┐
│   Gmail Account     │  Inbox / Archive / Trash
└─────────────────────┘

Step-by-step setup instructions

Step 1: Ensure prerequisites are met

Before configuring MCP, ensure:

1. You have an active PureBox account.
2. Your Gmail account is connected and scanned at least once.

Step 2: Configure your AI client

#### Connecting in Claude (Web & Desktop)

1. Open Claude Settings and navigate to Connectors.
2. Click Add Connector (or Custom MCP Server).
3. Enter the PureBox MCP URL:

`` https://api.purebox.ai/mcp ``

1. Complete the OAuth verification challenge to link your PureBox account.

#### Connecting in Cursor / Windsurf

1. Open Cursor Settings > Features > MCP.
2. Click + Add New MCP Server.
3. Select type SSE / Remote.
4. Set the URL to https://api.purebox.ai/mcp.
5. Authorize the browser prompt when requested.

#### Connecting in Claude Desktop via configuration file For local developer setups, add the server to your claude_desktop_config.json:

{
  "mcpServers": {
    "purebox": {
      "url": "https://api.purebox.ai/mcp"
    }
  }
}

Available MCP tools

Once linked, your assistant gains access to dedicated analytical tools:

Example conversational prompts

Once connected, you can interact with your mailbox conversationally:

• *"Check PureBox to see if my mailbox scan has completed."*
• *"Summarize the top 5 high-volume marketing senders currently cluttering my inbox."*
• *"How many messages are recommended for Archive versus Trash in the current suggestions?"*
• *"Prepare an apply plan to archive newsletters older than 30 days and show me what was selected."*

Because destructive actions require server-side plan confirmation, your assistant can help you analyze and organize your inbox without the risk of unintended data loss.

Revoking access and managing security

You retain complete control over connected AI tools. To disconnect an assistant:

1. Log in to your PureBox web dashboard.
2. Navigate to Account > Assistant access.
3. Locate the connected assistant and click Revoke.

Revoking an assistant immediately invalidates its MCP bearer token without disrupting your primary Gmail connection.

Summary

The Model Context Protocol turns AI assistants from generic text generators into context-aware productivity partners. By integrating PureBox's hosted MCP server (when your assistant client supports Remote MCP over OAuth), you can use conversational triage while preserving token isolation, documented privacy boundaries, and explicit human approval over mailbox actions.

Editorial verification and legal remarks

Fact-check & legal notice (as of 2026-10-22): Client connection steps for Claude, Cursor, Windsurf, and ChatGPT reflect third-party MCP client interfaces as of 2026-10-22; successful connection requires an assistant client that supports Remote MCP over OAuth and an existing PureBox account with Gmail connected. Third-party trademarks belong to their respective owners. For PureBox's binding data-handling and subprocessor commitments, see our Privacy Policy, Terms of Service, Sub-processors list, and B2B Data Processing Addendum.