Learn what a letter of agreement is and how to write one, including a template and example to help you get started crafting your own. 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.How to write an agreement. Write agreement yourself or get help. FIRST SUPPLEMENTAL LETTER OF AGREEMENT TO CONTRACT C-130546. A settlement agreement is between parties in a legal dispute — the Plaintiff (initiating) and Defendant (defending). In the body of the letter or MOU, list the main points of the agreement and provide specific, thorough information wherever possible. Fill it up smartly and sign digitally. The agreement describes the property, specifies the monthly rent, and lists the responsibilities of both parties. The parties to this Letter of Agreement (LOA) are the City of Los Angeles (City) and the.