When you want to define the terms of a working relationship between two or more parties, consider writing a letter of agreement. A simple agreement letter template so you can fill in the details and get it signed.Fill, deliver, and sign this free agreement in minutes! A Letter of Agreement is a document that outlines the terms and conditions of an agreement between two parties, like a more concise version of a contract. This State of New York Letter of Agreement and its Appendix A Federally Funded. A letter agreement is a written legal document that is made between two parties who want a simple way to make their discussions of a transaction official. Ensure clarity and protection in your business relationships with our general agreement template. Create and download your agreement for free!