Cloud sessions can use this machine's MCP servers after you agree

What

MCP servers are outside programs that give Claude extra tools. A cloud session, started with --cloud, runs away from your machine. It can now call MCP servers configured on your machine, through that machine, if you allow it. The device-mcp-consent.json and device-mcp-snapshot.json state files that were already reserved are now used for this.

• Consent: a dialog asks "Let cloud sessions use this machine's MCP servers?" with "Yes, offer this machine's MCP servers", "No, keep them to this machine" and "Not now". Focus starts on "Not now", and nothing is offered until you allow it. Your answer is saved in device-mcp-consent.json, tied to the machine's hostname and to the terms it was given under.
• Local control: the servers keep running on your machine with their saved logins, and your machine's allow, deny and ask rules still decide each call.
• Which servers: only stdio, http, sse and ws servers are offered. sdk, IDE and claudeai-proxy servers are left out. Servers deployed by an administrator are never offered, and servers defined by a project are not offered yet.
• Tool changes: the tools each server listed are saved in device-mcp-snapshot.json. If a server's tools change after you approved it, it is held back until you approve again. The prompt says "An MCP server on this machine changed its tools" or "MCP servers on this machine changed their tools".
• Tools can be dropped for name clashes, deny rules, your organization's permission limit, name length, definition size, schema depth, or limits on how many tools and how much data are announced. Enterprise and managed settings take priority, and dropped tools are listed under "Not offered to the cloud session:".
• If a call fails, the error says clearly whether the tool did not run or may have run.

The flag tengu_device_mcp_serving has not been read.

Why

A cloud session can reach tools and logins that live only on your laptop. The consent and re-approval prompts, and your local permission rules, decide what it can use.