So, for your assignment proposals, you would list (in either essay or point form) the full set of criteria by which your project can be gauged to have failed. for example "Our project will have failed if:"
- the project does not advance an academic thesis.
- the project does not have [some measurable degree of] quality
- the project does not identifiably incorporate material from relevent scholarship
- the project fails to relate directly to some number of the primary course texts
- the project fails to represent and demonstrate advanced understanding of the central ideas of the course
- &c, &c.
Additionally, proposals are accompanied by a concise justification of the academic validity of the project being proposed.
An effective proposal describes (nb. look up the etymology of this word in the OED) three components of a project:
Two pages is a reasonable length for a proposal of this type, four pages at most.