[wolverine876]

You confuse 'agreeable' - admittedly an ambiguous term - with 'walkover'. You can negotiate both with strength and without being a monster yourself.

[LeroyRaz]

When agreeable was first used in the chain of comments above it was presented as the counter point to "scary." As in, you defend yourself by appearing scary to take on.

Shrewd tactful negotiation can be valuable, but I think people are mainly emphasizing the need for strength and clear emphatic boundaries, not for being a "monster."