All Washington landlords must provide mold disclosure information to tenants. The mold disclosure must be a document approved by the Washington Department of Health. Providing a mold addendum will not satisfy the law, unless the mold addendum incorporates a Department of Health approved mold disclosure form. The Department must mail the mold disclosure form to the landlord in a printed format upon request. 
Landlords and property managers are immune from civil liability for failure to give the mold disclosure except where such failure is knowing and intentional.
Lead based paint disclosure.
All landlords in the US must provide a federally approved lead based paint disclosure form for buildings constructed prior to 1978. The lead based paint disclosure must be the form approved by the federal Environmental Protection Agency (EPA).
Failure to abide by the lead based paint disclosure law may result in civil penalties assessed by federal EPA regulators. Often the EPA is only seeking compliance, and will adjust or waive penalties if landlords and/or property managers bring their practices into compliance. Nonetheless, a knowing violation may result in treble damages and costs, including attorney fees and expert witness fees.
Washington landlords are required to provide a written receipt for all cash payments (whether or not the tenant requests a receipt), and for all non-cash payments upon request.
Copies of the rental agreement.
Washington landlords must provide tenants an executed copy of the rental agreement to each tenant who signs the rental agreement. Tenants are entitled to one free replacement copy of the rental agreement during the tenancy.
Washington residential landlords must designate the name and address of the landlord either in the rental agreement or conspicuously posted notice. The “landlord” under the Residential Landlord-Tenant Act may be the owner, lessor, or designated representative such as an agent, resident manager, or designated property manager.
Seattle tenant information and voter registration packet.
Seattle landlord-tenant law requires residential landlords to provide a tenant information and voter registration packet to all tenants. If the landlord fails to provide the tenant with the tenant information and voter registration packet, the tenant may give notice and terminate the rental agreement, and may also sue the landlord in a private cause of action.
Seattle criminal history screening prohibition notice.
Seattle residential landlords are required to give notice that they are prohibited from requiring disclosure, asking about, rejecting an applicant, or taking an adverse action based on any arrest record, conviction record, or criminal history. Violations of this law can subject the landlord to penalties of up to $55,000.
This is a short summary of some written disclosures the law requires landlords to provide to tenants.  If you are unclear about the legal rights and obligations of landlords and tenants you should consult with a lawyer. 
 For a current list of downloadable approved forms, see the Dept. of Health website at https://www.doh.wa.gov/YouandYourFamily/HealthyHome/Contaminants/Mold/RentersLandlordsandMold (last accessed 11/2/17).  RCW 59.18.060(13), (14).  42 U.S. Code § 4852d. The current form is posted on the EPA website, or may be obtained from real estate brokers or landlord associations. See https://www.epa.gov/sites/production/files/documents/lesr_eng.pdf (last accessed 11/2/17).  42 U.S. Code § 4852d.  See, for example, Real Estate Notification and Disclosure Rule Interim Final Enforcement Response Policy, EPA; Office of Enforcement and Compliance Assurance; Office of Civil Enforcement; Waste and Chemical Enforcement Division (December 2007).  42 U.S. Code § 4852d(b)(3),(4).
 RCW 59.18.063.  RCW 59.18.065.  RCW 59.18.060(15).  RCW 59.18.030(14).  SMC 7.24.060, 7.24.080.  SMC 14.09.020.  SMC 14.09.100.