This addon is good and needed, but users would also benefit from many more features/fixes and additonal OpenSearchDescription:

(1) Fix "strict_min_version" from "65.0" to "56.6". WaterfoxClassic has the following in its User-Agent string: "Gecko/20100101 Firefox/68.0 Waterfox/56.6.2022.04"; so, WaterfoxClassic is technically forked from Firefox 56.6, but yet advertises Firefox 68.0 compatibility. This means that after this addon is installed to WaterfoxClassic, while the addons still seems to work as expected on WaterfoxClassic, on the Addon-Manager page, WaterfoxClassic reports a warning "DuckDuckGo Onion is incompatible with Waterfox 56.6". So, fixing "strict_min_version" will fix this minor issue for WaterfoxClassic users.

(2) Fix the template to have "q=" at the end. So, instead of "https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/?q={searchTerms}&t=newext", fix to "https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/?t=newext&q={searchTerms}" . This makes it easier for users to invoke new searches by easily editing the final part of the URL.

(3) Add another OpenSearchDescription for "DuckDuckGo Onion Lite" using template: "https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/lite?q={searchTerms}". DuckDuckGo-Lite is a lightweight version of DuckDuckGo that loads very-fast, consumes minimal resources, and works perfectly even without javascript enabled, making it perfect for those users who have many hundreds (or even thousands) of tabs open at the same time.

(4) Add another OpenSearchDescription for "DuckDuckGo Onion Images (All Sizes)" using template: "https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/?iax=images&ia=images&q={searchTerms}"

(5) Add another OpenSearchDescription for "DuckDuckGo Onion Images (Large Size)" using template: "https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/?iax=images&ia=images&iaf=size%3ALarge&q={searchTerms}"

(6) Add another OpenSearchDescription for "DuckDuckGo Onion Images (Wallpaper Size)" using template: "https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/?iax=images&ia=images&iaf=size%3AWallpaper&q={searchTerms}"

(7) Add another OpenSearchDescription for "DuckDuckGo Onion Videos (All Durations)" using template: "https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/?iax=videos&ia=videos&q={searchTerms}"

(8) Add another OpenSearchDescription for "DuckDuckGo Onion Videos (Long Duration)" using template: "https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/?iax=videos&ia=videos&iaf=videoDuration%3Along&q={searchTerms}"

(9) Add another OpenSearchDescription for "DuckDuckGo Onion POST (not GET)" using the following XML (since POST is sometimes preferred for better privacy - for users who some-time/all-the-time do not want their searchTerms to be disclosed in the URL address):

NOTE: AMO won't let me add XML to this review, so angle brackets must be substituted for the double-underscores:

__Url type="text/html" method="post" template="https://duckduckgogg42xjoc72x3sjasowoarfbgcmvfimaftt6twagswzczad.onion/lite/"__
__Param name="q" value="{searchTerms}"/__
__/Url__


Implementing the above features/fixes will make this addon much more compatible, robust, powerful, versatile and useful.

Thanks!