I believe that an Agreement must, in order to be useful across organizational boundaries, be regardable as a Contract. 
In order to meet this requirement, a few requirements must be added overall:

1) Both parties to the contract must (digitally) sign it.
2) Both parties must end up with their own copy of the contract.

With this, either party that gets dissatisfied with the contract can go to an independent third party (such as a civil 
court) and argue their case for compensation.

To meet the first requirement based on WS-Agreement requires that the Agreement Initiator digitally sign the 
AgreementOffer, and to meet the second requirement the Agreement Provider must respond with the offer digitally signed 
additionally by the provider (assuming she agrees to it, of course). Presumably the provider would also retain a copy in
 secure storage (much as companies keep paper copies of contracts in fireproof safes) but that is outside the scope of 
wsag.

Note that having the agreement live in a service is *not* sufficient to meet this requirement, since it is not possible 
to strictly prohibit the provider from tampering with the document, and nor is it possible to prevent either side from 
destroying the agreement resource (something which it would be highly advantageous to do if the other side was taking 
the matter to court!)

Of course, such contract-related things do not inherently say anything about the monitoring of the agreement, and they 
also significantly increase the computational cost of actually reaching the agreement. On the other hand, it means that 
all parties remain able to clear up any disputes they have over the agreement (ultimately a good thing for the overall 
grid, even if one of the parties would not agree in the short term).