Center booking connector

What it does

• Finds businesses published on Center.
• Answers questions from a business's public facts only.
• Checks open times.
• Books for the signed-in person, with their approval.

It is separate from the person's own Center errands server.

Endpoint and discovery

https://app.center.com/mcp

Streamable HTTP: one JSON-RPC message per POST, as application/json. GET and DELETE answer 405.

Authorization (OAuth 2.1)

1. With no bearer token, POST /mcp answers 401 with a WWW-Authenticate challenge that names the protected-resource metadata and the scopes.
2. The assistant reads the discovery documents and registers itself. Clients are public only (token_endpoint_auth_method: none). Redirects must be https, or http on loopback; they match exactly, and a loopback redirect may use any port.
3. The person opens the consent page. The request must carry code_challenge with code_challenge_method=S256 (PKCE S256 is required; plain is refused), state and resource. When resource is present it must be https://app.center.com/mcp.
4. The person signs in with a one-time code sent by text to their phone. Email sign-in is not available yet.
5. The consent page names the assistant (as it registered itself), the scopes, and exactly what a business receives when the person books. The person chooses Allow or Don’t allow.
6. A single-use code (10 minutes) returns with state and iss (RFC 9207). The token exchange checks the PKCE verifier and returns an access token (1 hour) and a refresh token (60 days). Refresh tokens rotate on every use; reusing an old one revokes the whole link. Tokens are bound to https://app.center.com/mcp.

Credentials are opaque. Center stores only their SHA-256 digests.

Scopes

Any signed-in person may use the read tools. A booking tool called without bookings.write gets HTTP 403 insufficient_scope and a step-up challenge.

Tools

The connector only sees published businesses. Each result is built field by field from the public record.

A price is stated only when the owner confirmed it or it comes from the business's own public page. Any other price reads "price not published", never $0. A business with nothing bookable online returns booking_supported: false with how to book (its booking or reservation link and its phone).

Deposits

The connector does not take payments, and money never moves through an assistant. When a service collects a deposit or the full price at booking, prepare_booking refuses with deposit_required. The refusal carries the deposit amount when it is published, plus the business's booking page and phone. Nothing is held, and nothing is booked without the deposit the business requires.

Errors

• No valid token: HTTP 401 with the RFC 9728 challenge (WWW-Authenticate: Bearer resource_metadata=…, scope=…).
• Missing scope: HTTP 403 insufficient_scope.
• Past a rate limit: HTTP 429 with Retry-After, and a JSON-RPC error whose data is {error: 'rate_limited', retry_after_seconds}.
• A tool refusal is a tool result with isError: true and structuredContent: {error: <reason>, message, …}.

Reasons:

• invalid_arguments
• business_not_found
• service_not_found
• service_not_bookable_online
• booking_not_supported
• deposit_required
• slot_unavailable
• proposal_not_found
• proposal_expired
• terms_changed
• booking_not_found
• cancel_window_passed
• already_cancelled
• test_account_real_business
• booking_unavailable
• ask_unavailable

Rate limits

Per minute:

Each address may make up to 600 requests a minute to /mcp, because assistants call from shared addresses.

Privacy

• Facts come only from a business's public record. No tool reads a business's clients, bookings or conversations.
• Times are open times only: the connector never says who holds another time, never names another client, and never gives a staff member's private details.
• A person sees, cancels and moves only the bookings they made through the connector. Anyone else's booking reads booking_not_found.

When the person books, the business receives the name on their Center account and their verified phone. The consent page says so before they allow access.

Support and policies

Questions or problems: help@center.com

• Privacy Policy
• Terms of Service