It does not get improvised outside
Connecting directly solves the afternoon and creates a piece nobody can see. The day that connection fails, there will be nowhere to look.
Capabilities
It asks for what it needs and the door takes care of it. That is the whole promise: same credential, same record, whatever the service and whatever the day.
One credential · one record · any service
The catalogue
Grouped by what it solves, not by the technology serving it. An agent asks for "this site's analytics", not for an endpoint.
The list grows. What does not grow is the number of doors.
Bringing things in
An agent needs a capability that is not there. That is the interesting moment, because it is where a system either rots or gets stronger.
Connecting directly solves the afternoon and creates a piece nobody can see. The day that connection fails, there will be nowhere to look.
Whatever is added becomes available to any agent, with the same credential and the same record as the rest. The work is done once.
The difference
What comes through here leaves a trail. What connects on its own does not — and therefore, as far as the system is concerned, never happened.
Knowing what each agent spends requires everything to go through the same place. It is the kind of number you only have if you designed for it.
When a service changes, you fix it at the door. The alternative is fixing it in every consumer and finding them one by one as they break.
Retiring a capability matters as much as adding one, and it is only possible if you know who was using it.