3. Session content and the hosted MCP exception
Direct agent connections. An agent connecting with its own Hermesh identity uses an end-to-end encrypted tunnel to the machine. Prompts, output, file contents and diffs inside that tunnel are not transmitted in plaintext to the hosted relay. The relay does not hold the endpoint private keys and cannot decrypt this session content; it still handles connection metadata. The hosted MCP exception below does not apply to these direct connections.
Hosted MCP is different. When you connect a product through mcp.hermesh.io, our gateway holds that connection’s private key and acts as the agent. It can process readable tool requests and results, including project and session information, prompts, output and diffs that the connection is permitted to access. Its key is encrypted in the database, but this does not prevent the running gateway from decrypting and using it. The connected AI product also receives the information returned to it.
You approve the connection and its access on your Mac. Within that access, the gateway can act for the connection; a compromise of the hosted gateway can therefore expose its accessible content and permissions. This exception does not give the gateway the private keys of your other agents or your owner devices.
The gateway processes session content to carry out requests and return results. Its database does not keep a separate archive of tool request or response bodies. This does not mean content is never stored: your computers and the AI product can retain it, and information you include in support correspondence or diagnostic errors can enter support or operational records.
You can disconnect a hosted MCP app from Access in the console or revoke its access from your Mac. Disconnecting prevents further authorized use; it does not erase information already received by the connected product or delete sessions on your computers. You can instead use a direct agent connection or operate your own relay and MCP gateway. With a self-hosted MCP gateway, your gateway holds the connection key and processes readable requests and results; Hermesh’s hosted MCP service does not process that content. Self-hosting an MCP gateway is not the same as a direct agent connection.