Update a contact name / tags / custom attributes
{id} is the contact phone (E.164) by default, or its BSUID with ?identifierType=bsuid. Tags accept a full-replacement array or an { add, remove } delta; attributes merge (a null value deletes the key).
At least one of name, tags or attributes is required — enforced by a cross-field rule the schema below cannot express, so an empty body is 400 invalid_request. An { add, remove } tag delta must itself carry a non-empty add or remove array.
Required scope: contacts:write
Authorizations
Project API key issued in Settings → API keys. Send it as Authorization: Bearer pk_live_….
Headers
Target project id, for an MCP OAuth bearer (mcp_at_…) attached to more than one project — get ids from GET /v1/projects. Matched case-insensitively.
Omit it and a READ falls back to the connection's default project; a mutation (any non-GET) on a connection with 2+ projects is rejected with 400 project_required — a write is never defaulted to a guessed project. A connection with exactly one project never needs the header.
Scopes are checked against the SELECTED project only, never a union across the connection.
For a pk_ API key the header selects nothing — one key is one project's context — but it IS validated: omit it and the key's own project is used, send it and it must name that project, otherwise the call is rejected with 403 project_not_attached (a blank value is 400 invalid_project_header, as above).
Path Parameters
Query Parameters
phone, bsuid 