Other programs can reach your room. Each way in runs as your account: your credit, your seats, your team's rules. Nothing here can act as anyone else.
The room as an MCP server
The endpoint /api/mcp at letthemchat.com speaks the Model Context Protocol, so an assistant with MCP connectors can start discussions and read answers.
Where to find it. In the assistant, not in our Settings. Add a custom connector with the address https://letthemchat.com/api/mcp and OAuth as the authentication. It sends you to sign in; there is no key to paste.
| Tool | What it does |
|---|---|
| start_discussion | Starts one in the background and returns its id |
| get_discussion | Status, transcript so far, and the agreed answer once there is one |
| list_discussions | Your twenty most recent |
| list_running_rooms | Discussions running now or active in the last two hours |
| spend_summary | Spending by project for today, this week or this month |
| list_schedules | Your schedules and how each last ended |
| run_schedule | Starts a schedule now, if it runs on the server |
| recent_audit_events | The team's recent audit events, for owners, admins and auditors |
Twenty calls a minute per account. A discussion takes one to several minutes, so poll get_discussion rather than waiting on it.
When not to use it. For work in your repository: an MCP-started discussion runs on the server, with no checkout.
The Mac is also an MCP client: Settings → The room → Plugins adds servers your seats can use.
The room as an A2A agent
Another company's orchestrator can call the room over Agent2Agent. Its agent card is at /.well-known/agent-card.json, and /api/a2a takes message/send, tasks/get and tasks/cancel. Every call needs a bearer token, either an OAuth access token or an account API key. The audit trail records which client sent each task.
Another agent as a seat
The other direction is on the Mac. A seat's Key menu can hold an external A2A agent, configured by its agent card's address. It reviews and never leads, its answer is quoted to the room as material to judge, and a task that stalls for two minutes is cancelled so the discussion goes on. It is a bring-your-own power, so on Free it runs for the 14-day trial.
The HTTP API
Everything the apps do goes through a documented API, with OAuth 2.1 and PKCE for third-party clients. An account API key also opens an OpenAI-compatible endpoint at /api/v1/chat/completions that spends the account's credit; minting a key needs Pro or Team (Settings → Account → Connected → API keys).
For coding agents
/llms.txt is an index of these docs for an agent to read first, and /agent-onboarding/SKILL.md tells a coding agent how to set the product up for its user. Both are served on letthembuild.com and letthemchat.com.
Further reading. Model Context Protocol specification, MCP project. Agent2Agent Protocol Specification, A2A project. RFC 6749 OAuth 2.0, IETF, 2012. RFC 7636 PKCE, IETF, 2015.