MCP Data Privacy Explained
How MCP handles your data. Clear explanation of data flows, storage, and privacy protections.
This article is part of our Security series.
Read the complete guide: Is MCP Safe?When you connect Claude to your email and files, where does that data actually go? Who can see it? How long is it kept? This article explains exactly how MCP handles your data—no vague reassurances, just clear answers about data flows, storage, and privacy.
The Data Flow: Step by Step
To understand privacy, you must follow the data. Let's trace what happens when you ask Claude to "Summarize my unread emails".
You type a prompt in Claude Desktop. This prompt is sent to Claude's API.
Claude determines it needs to access Gmail and sends a request back to your computer (the local MCP server).
The MCP server running on your machine uses your local credentials to access Gmail and retrieve the emails.
The email content is sent to Anthropic's API for processing. Claude generates the summary.
The summary is displayed in your Claude Desktop.
Your Tools (Gmail, Drive)
↓ [Your credentials]
MCP Server (Your computer)
↓ [Data for processing]
Claude API (Anthropic)
↓ [Response]
Claude Desktop (Your computer)
Key Insight: Your data touches three places: your tools, your computer, and Anthropic's API. There is no "MCP Cloud" storing your data in the middle.
Where is Data Stored?
It's important to distinguish between processing and storage.
On Your Computer
Permanent Storage.
Your configuration files, API tokens, and local logs live here. The MCP servers themselves run here. This is why you must secure your device.
On Anthropic's Servers
Temporary Processing & History.
The conversation history (including data fetched from tools) is stored to sync across your devices, unless configured otherwise.
Data Retention Policies
How long does Anthropic keep the data sent via MCP?
By default, Anthropic retains API inputs/outputs for 30 days to identify abuse, after which they are deleted.
Enterprise customers can qualify for zero-retention policies where data is not stored after processing.
For Claude Pro and API users, Anthropic does not use your data to train their generative models.
Encryption & Security
How is data protected while moving?
- In Transit: All communication between your computer and Anthropic's API is encrypted via TLS 1.2+.
- At Rest: Data stored on Anthropic's servers is encrypted at rest (AES-256).
- Local Communication: The connection between Claude Desktop and local MCP servers happens over
stdio(standard input/output) pipes on your machine, not over the network. This means local traffic is isolated within your device.
The Third-Party Variable
Important Warning
MCP is an open protocol. Anyone can build an MCP server.
If you install a Community or Third-Party MCP server, you are running their code on your machine. That code could theoretically have vulnerabilities or malicious logic (like sending your data to a different server).
Your Controls
You are not powerless. You have specific controls over your privacy:
You choose exactly which tools to connect. Don't want Claude reading email? Don't connect Gmail.
Claude cannot access data in the background. It only acts when you prompt it.
You can delete conversation history from Claude, which removes the associated context data.
You can uninstall an MCP server at any time by editing your config file.
The Bottom Line
MCP does not create a "magic cloud" that sucks up all your data. It creates a bridge between your local tools and the Claude API.
Your data is safe if:
- You trust Anthropic (Claude).
- You trust the specific MCP servers you installed.
- You secure your own computer.
If you are comfortable using Claude via the web interface, using it via MCP implies very similar privacy characteristics—just with more capabilities.