Because we generate the URIs at the backend by replacing %s with params, we don't take into account the annos that specify the post data. We can reuse the existing front-end POST data code by just having the "url" show up as the plain keyword search. This should get fixed by bug 445955.

Per policy at https://wiki.mozilla.org/Bug_Triage/Projects/Bug_Handling/Bug_Husbandry#Inactive_Bugs. If this bug is not an enhancement request or a bug not present in a supported release of Firefox, then it may be reopened.