---
title: "What is MCP (Model Context Protocol)?"
description: "MCP is the open protocol that lets an AI agent call another product's tools directly. In direct mail, it lets an agent build audiences and draft pieces while a person approves every send."
canonical: https://trysincerely.com/glossary/mcp
last_updated: 2026-08-29
---
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# What is MCP (Model Context Protocol)?

> MCP is the open protocol that lets an AI agent call another product's tools directly. In direct mail, it lets an agent build audiences and draft pieces while a person approves every send.

Source: https://trysincerely.com/glossary/mcp

MCP (Model Context Protocol) is an open standard that lets an AI agent call another product's tools directly, instead of a person copying data between windows or a developer writing glue code for every integration. Anthropic introduced it in late 2024, and the major agent clients now speak it. An agent connected to a direct mail platform over MCP can build an audience, check addresses, and draft pieces, then hand a person the decision to send.

## Why it matters

Before MCP, giving an agent access to a product meant a custom integration: read the REST docs, manage an API key, write and maintain the code that translates between the model and the endpoints. MCP replaces that with one protocol. The client registers itself with the server, the person signs in through OAuth, and the agent receives tools it can call with the same authority that person already has, and no more.

Direct mail raises the stakes on that arrangement. Most MCP tools read and write data that can be corrected later. A tool that sends mail spends money on a call that cannot be taken back once a print vendor accepts the piece. So for mail, the definition of a good MCP server includes what it refuses: consequential calls should stop at a confirmation a human has to click, enforced by the server rather than requested in the prompt.

## Example

You tell Claude Code to write to the 12 accounts that went quiet since March. Over MCP, the agent queries your CRM sync, verifies each mailing address, and drafts 12 individual notes. Then it stops. A confirmation card lists the recipients, the design, and the price, and only your click releases the pieces to print.

What that looks like in practice is covered in [physical mail MCP](https://trysincerely.com/guides/physical-mail-mcp), and the connection steps live in [how to send direct mail from your AI agent](https://trysincerely.com/integrations/mcp-agents).

MCP gives the agent hands. The confirmation gate decides what those hands are allowed to hold.

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Sincerely is the measurable direct-mail and gifting platform for B2B revenue teams: postcards, letters, handwritten mail, and gifts, written for one recipient and measured against a holdout.

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