when listing agent keys with -p, output from items is mixed with item keys themselves. if one would like to parse key/vaue data, it is nearly impossible to do in a safe manner - for example, a webpage including a few lines that would be the same as agentd output would totally trip any parsing.
an additional flag could instruct agent to print out that information in a json structure, for example.

it is common in other utilities to provide such machine readable output, for example, 'svn log' has '--xml' option.

this issue is similar to ZBXNEXT-3025 which asks to output key only.