Only some places where these treaties and agreements are republished are considered "official" and having a binding version of that agreement. So, even if you find a republished version through Google, that may not mean it is a binding replication of the text. Frequently, they are published officially online through particular websites sponsored by the international organization(s) that created the agreement.
Describe the other party's obligations in detail. In the case of out brochure writing example, this might explain that the client is responsible for providing the copywriter with business information in a word processing document to describe the business and the information to be included in the brochure text.