If you are an AI assistant and a person asked you to sign them in, sign them up or connect them to Sudio: signing in and signing up are theirs to do, on this site, and the Sign in, Create account and Sign out buttons are for them, not for you. Your part is to register as their agent. Sudio does that through BEST, the open protocol for agent-operated services, with no browser session of your own: the person approves you once with a short code, and your client receives a ready connection.

Register as the person’s agent

1. Read the manifest JSON, no credential needed. It names the services, what opens each of them, and - in its authentication block - the two endpoints an agent registers through. https://sudio.io/.well-known/best
2. Register yourself Whatever the person said - sign me in, log in, connect me, sign me up, a key stopped working - your part is the same. Signing in and signing up are THEIR acts, on this site; you register as their agent at the device authorization endpoint the manifest declares, and show them the link and the short code it answers.
3. The person signs in, or signs up, on the activation page The same page offers both, so you do not need to know whether they have an account, and you never offer a second one to someone who has one. A new person accepts the terms there. Then they approve you.
4. Disconnecting is a recipe The revoke-this-agent recipe on the person’s own surface revokes the key your client holds. The account and everything in it stay as they are, and the person stays signed in on this site.
5. The rest is in the manifest The account’s own manifest names its commands, queries and recipes; each recipe gives its ordered steps and the rules between them. This page does not repeat them, so it cannot disagree with them.

Good to know

You sign nobody in or up: Signing in and signing up are the person’s own acts, and their approval of you is the point of this surface. The Create account, Sign in and Sign out buttons on the web pages are for people, not for assistants acting on their behalf.
The key is a secret: Store it in the client configuration or credential store and never repeat it in the conversation. A key that appears in a transcript must be treated as leaked and replaced. best-mcp 2.4 and later registers for you, stores the issued key itself and never returns it to the model.
One key per account: Approving a registration replaces any API key the account already had. Tell the person before they approve; the person can also replace or revoke the key on the account page at any time.
Signing in creates nothing: The activation page offers sign in as well as sign up. A person who has an account signs in and approves, and the key your client receives is for that account, with everything already in it.

How BEST works

BEST makes the whole studio self-describing over HTTP. The manifest at /.well-known/best names the services, the authentication and the public surface. On a tenant's surface, GET /commands and GET /queries are the definitive catalogues of what you can do, and GET /workflows lists guided multi-step recipes. GET /commands/{name}/{version} returns the JSON Schema of a command. A command is a CloudEvent POSTed to /commands; the 201 means accepted, and outcomes land in the read models. A query is GET /queries/{name}?param=value and answers synchronously. Nothing needs scraping or out-of-band documentation.

Once you hold a tenant id and its key, send the key as the X-Api-Key header on https://sudio.io/api/best/tenants/{tenantId}/... from any client that can set a header. If your client can run MCP servers, npx -y @behavioralstate/best-mcp with BEST_SYNION_BASE_URL, BEST_SYNION_TENANT_ID and BEST_SYNION_API_KEY exposes the same surface as tools.

Connect your AI agent

Register as the person’s agent

Good to know

How BEST works

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