Search in Seller Central for Amazon Solutions Business Services Agreement, then scroll down to Section 9 Insurance.

There you will find a bit of text that reads like this;

If the gross proceeds from Your Transactions exceed the applicable Insurance Threshold during any month if the Elected Country is the United States, or each month over any period of three (3) consecutive months if the Elected Country is Canada or Mexico, or otherwise if requested by us, then within thirty (30) days thereafter, you will maintain at your expense throughout the remainder of the Term for each applicable Elected Country commercial general, umbrella or excess liability insurance with the Insurance Limits per occurrence and in aggregate covering liabilities caused by or occurring in conjunction with the operation of your business, including products, products/completed operations and bodily injury, with policy(ies) naming Amazon and its assignees as additional insureds. At our request, you will provide to us certificates of insurance, the full insurance policy, or other documents we may request for the coverage to the following address: c/o Amazon, P.O. Box 81226, Seattle, WA 98108-1226, Attention: Risk Management.

Further scrolling down to Definitions you will further find some additional clarification along these lines;

"Insurance Limits" means the applicable one of the following:

• One Million Canadian Dollars ($1,000,000) (if the Elected Country is Canada),
• Ten Million Mexican Pesos ($10,000,000) (if the Elected Country is Mexico),
• One Million U.S. Dollars ($1,000,000) (if the Elected Country is the United States).

"Insurance Threshold" means the applicable one of the following:

• Ten Thousand Canadian Dollars ($10,000) (if the Elected Country is Canada),
• One Hundred Thousand Mexican Pesos ($100,000) (if the Elected Country is Mexico),
• Ten Thousand U.S. Dollars ($10,000) (if the Elected Country is the United States).

Which establishes the approximate amounts of minimum liability coverage you need. Of particular note is the little line about naming Amazon as an additional insured, and proving it by submitting documents upon request. Amazon has started asking everyone, regardless of the dollar amount of sales for their properly executed ACORD 25.