Before asking the question, I need to give some background information:
The Rambam in Hilkhoth Berakhoth 1:11 says,
כָּל הַשּׁוֹמֵעַ בְּרָכָה מִן הַבְּרָכוֹת מִתְּחִלָּתָהּ וְעַד סוֹפָהּ, וְנִתְכַּוַּן לָצֵאת בָּהּ יְדֵי חוֹבָתוֹ--יָצָא, וְאַף עַל פִּי שֶׁלֹּא עָנָה אָמֵן
"Everyone who hears a berakhah from [any of the categories] of berakhoth from its beginning to its end, and intends thereby to fulfill his own obligation, has fulfilled his obligation, and [it is so] even if he did not answer Amen."
It is apparently assumed that the Rambam is of the opinion, expressed in the Shulhan Arukh (cf. Orah Hayyim 213:3), that in order for the listener to be yossei yedhei hovatho he must not only hear every word of the berakhah being recited, but the one reciting it (the mevarekh) must also have the specific intention of being mossi yedhei hovatho. Basically implying that both the mevarekh and the one listening to him (the shomea) must have made some sort of agreement beforehand that each would have the other in mind. However, from the plain reading of the Mishneh Torah, it would seem that Rambam holds that the intention to fulfill one's obligation is only required on the part of the one who hears. Further, no mention is made of the mevarekh and the shomea making prior arrangements to have each other in mind.
Anyone who is familiar with the style of the Rambam knows the he says what says and what he doesn't say he doesn't say. In other words, if the Rambam makes no mention of the requirement of intention on the part of mevarekh, then it would seem that he does not hold it to be necessary for the shomea to fulfill his obligation. This is the general rule, with the exception of some cases - such as natilath yadhoyim where the entirety of halakhoth regarding it are found in Hilkhoth Berakhoth 6, with the exception of the halakhah of being meshafshef ones hands, which is found all the way toward the end of the Mishneh Torah in Hilkhoth Miqwa'oth 11:2(3). So, if anyone knows of another place in the Rambam which speaks about this halakhic subject, please let me know.
In researching this halakhah in the Rambam, I have read the available nosei kelim (which are the Kesef Mishneh and the Migdal Oz in this case), the pirush by Rav Yohai Maqbili shlit"a, the pirush of Mori Yusef (Rav Yosef Kapah) z"l, the Shu"T HaRambam, the Shu"T Rav Yehoshua HaNagidh, and the various Shu"Tim of Rav Ratzon Arusi shlit"a. In all of this I found that NONE of them discussed this question at all, with the exception of Rav Arussi who did not bring any textual support from the Rambam for the requirement of intention on the part of the mevarekh to be mossi the shomea, rather he said that le-aniyuth da`ato he held that it was required. Other than this, I have not found anyone who expresses an answer making an argument from the text of the Mishneh Torah itself.
One further piece of information: In Hil. Berakhoth 1:15 the Rambam states that we do not answer "Amen" after a child who is merely reciting berakhoth while learning. He then states וְהָעוֹנֶה אַחֲרֵיהֶן אָמֵן, לֹא יָצָא יְדֵי חוֹבָתוֹ ("And the one who does answer Amen [after the berakhah of a child reciting berakhoth for the sake of learning them] does not fulfill his obligation"). It would seem from this statement that the Rambam is dealing with a hava mina (assumption; pre-conceived notion) that intention is required only on the part of the shomea to fulfill his obligation but not on the part of the mevarekh since it is clear that a tinoq shel beth rabban (schoolchild) does not have the da`ath required to be mossi yedhei hovatho. It seems as if the Rambam is answering this hava mina by saying, "Your assumption is correct that intention is only required by the shomea, but this principle will not work in this particular case."
Does the Rambam hold that both the one who recites a berakhah and the one who listens BOTH need to have the other in mind in order for the one listening to fulfill his obligation thereby? Sources are greatly appreciated!