Wash. Rev. Code § 59.18 § 59.18.365

(1) The summons must contain the names of the parties to the proceeding, the attorney or attorneys if any, the court in which the same is brought, the nature of the action, in concise terms, and the relief sought, and also the return day; and must notify the defendant to appear and answer within the time designated or that the relief sought will be taken against him or her. The summons must contain a street address for service of the notice of appearance or answer and, if available, a facsimile number for the plaintiff or the plaintiff's attorney, if represented. The summons must be served and returned in the same manner as a summons in other actions is served and returned.
(2) A defendant may serve a copy of an answer or notice of appearance by any of the following methods:
(a) By delivering a copy of the answer or notice of appearance to the person who signed the summons at the street address listed on the summons;
(b) By mailing a copy of the answer or notice of appearance addressed to the person who signed the summons to the street address listed on the summons;
(c) By facsimile to the facsimile number listed on the summons. Service by facsimile is complete upon successful transmission to the facsimile number listed upon the summons;
(d) As otherwise authorized by the superior court civil rules.
(3) The summons for unlawful detainer actions for tenancies covered by this chapter shall be substantially in the following form:
Plaintiff/
Landlord/
Owner,
Defendant/
Tenant/
Occupant.
TO: . . . . . . . . . . . . (Defendant's Name)
. . . . . . . . . . . . (Defendant's Address)
GET HELP: If you do not respond by the deadline above, you will lose your right to defend yourself or be represented by a lawyer if you cannot afford one in court and could be evicted. The court may be able to appoint a lawyer to represent you without cost to you if you are low-income and are unable to afford a lawyer. If you believe you are a qualifying low-income renter and would like an attorney appointed to represent you, please contact the Eviction Defense Screening Line at 855-657-8387 or apply online at https://nwjustice.org/apply-online. For additional resources, you may call 2-1-1 or the Northwest Justice Project CLEAR Hotline outside King County (888) 201-1014 weekdays between 9:15 a.m. - 12:15 p.m., or (888) 387-7111 for seniors (age 60 and over). You may find additional information to help you at http://www.washingtonlawhelp.org. Free or low-cost mediation services to assist in nonpayment of rent disputes before any judicial proceedings occur are also available at dispute resolution centers throughout the state. You can find your nearest dispute resolution center at https://www.resolutionwa.org.
HOW TO RESPOND: Phone calls to your Landlord or your Landlord's lawyer are not a response. You may respond with a "notice of appearance." This is a letter that includes the following:
(1) A statement that you are appearing in the court case
(2) Names of the landlord(s) and the tenant(s) (as listed above)
(3) Your name, your address where legal documents may be sent, your signature, phone number (if any), and case number (if the case is filed)
This case □ is / □ is not filed with the court. If this case is filed, you need to also file your response with the court by delivering a copy to the clerk of the court at: . . . . . . . . . . . (Clerk's Office/Address/Room number/Business hours of court clerk)
WHERE TO RESPOND: You must mail, fax, or hand deliver your response letter to your Landlord's lawyer, or if no lawyer is named in the complaint, to your Landlord. If you mail the response letter, you must do it 3 days before the deadline above. Request receipt of a proof of mailing from the post office. If you hand deliver or fax it, you must do it by the deadline above. The address is:
. . . . . . . . . (Attorney/Landlord Name)
. . . . . . . . . (Address)
. . . . . . . . . (Fax - required if available)
COURT DATE: If you respond to this Summons, you will be notified of your hearing date in a document called an "Order to Show Cause." This is usually mailed to you. If you get notice of a hearing, you must go to the hearing . If you do not show up, your landlord can evict you. Your landlord might also charge you more money. If you move before the court date, you must tell your landlord or the landlord's attorney.