Google Home MCP puts your agent on the thermostat

Google opened early access to Home MCP today, and it moves agents from your files to your building. Google's developer docs describe a Model Context Protocol server that enumerates the rooms and devices in a structure, queries live device state, executes parameterized actions, and reads past states and chronological event logs. TechCrunch reports it is rolling out to Google Home Premium Advanced subscribers in the US at $20 a month, in English, starting now. If you run a shop, a clinic or a warehouse with Nest hardware in it, Google Home MCP is the first time a general-purpose agent can touch your physical premises.

What actually happened

Two servers shipped, and they are not the same product.

The first is Home MCP itself — the consumer-facing one. It runs behind a user-authorized OAuth flow, and Google names Antigravity, Open Claw and Claude as agents that connect to it. Setup is not one click: you create a Google Cloud project, configure it for Home MCP, hand the config to your agent, then sign in and grant permission. Google says agents cannot take sensitive actions on your behalf, but the docs do not enumerate which actions are fenced. Treat that as a claim until it is a list.

The second is Home Developer MCP, which grounds coding tools in the Home API reference, the Matter specification, and OpenThread and Thread docs. It works with Antigravity, Claude Code, Cursor and Copilot in VS Code. This one reads documentation. It cannot open a door.

Why it matters for your business

The device control is the headline. The event history is the risk, and it is the part nobody reads carefully.

A chronological event log across doorbells, cameras and motion sensors is a record of who came and went from your premises and when. Camera summaries are a written description of your staff's movements. Hand that to an agent and you have handed a third-party model provider an attendance log you never intended to create. That is a different conversation with your staff than "we automated the thermostat."

Separate the two grants. Your devs should connect Home Developer MCP today — it is documentation grounding with no premises access, and it makes Matter integration work meaningfully faster. Home MCP proper deserves a slower decision.

Read the OAuth consent screen as a contract. The grant is per-structure, not per-device. If your business Nest account and your home account sit under one Google identity, you are authorizing both. Split them before you connect, not after.

Do not put an agent on anything with a physical failure mode. Lights and thermostats degrade gracefully. Locks, gates and HVAC in a room with inventory do not. Keep those off the structure the agent can reach, or off Matter entirely.

Assume early access means the surface changes. Premium Advanced is a $20/month consumer tier, not a commercial SLA. Google declined to say when other tiers get it. Build nothing operational on a preview whose pricing and scope are both unannounced.

Sources: Google Home Developer Center, TechCrunch.