SP will not provide metadata file: maybe it's not necessary?

[shibboleth655 at lewenberg.com]

We are currently working with an external SP to authenticate against our 
IdP. This vendor insists that they don't need to give us metadata, only 
an entity ID, an SSO endpoint, and a desired nameid format. They don't 
sign requests or want responses encrypted; they are not part of InCommon 
or any other similar federation.

This vendor implies that an SP metadata file is not necessary. I realize 
that we could construct their metadata file for them with the 
information they provided, but, frankly, we don't want to: we feel it 
sets a bad precedent.

However, I am still new to Shibboleth, so I am thinking: maybe there 
_is_ some way to set up an SP in Shibboleth without corresponding 
metadata. Is there?

If not, and they are simply expecting us to construct the metadata for 
them, I am interested in the opinion of others who run IdPs: do you 
construct metadata for these sorts of SPs?

Thanks.

[Operating details: Shibboleth IdP version 3.2.1]