TCAS takes performance into consideration- it will give you a climb at max altitude, but one your residual performance can handle.
Afaik TCAS is NOT aware of actual performance limits, e.g. degraded performance due to loss of an engine, but some limits have been taken into consideration during certification.
http://www.faa.gov/documentLibrary/m...-55C_CHG_1.pdf :
(1) Aircraft not inhibited to climb when at maximum certified altitude should climb in response to TCAS climb RAs.
(2) Aircraft that are climb-inhibited from TCAS climbs at maximum certified altitude will be issued a “DO NOT DESCEND” RA.
and (courtesy of airbus)
AC 20-131A defines the maneuvers that the aircraft must be able to perform.
• In particular, the aircraft must prove that it can respond to a TCAS RA CLIMB order, even when it is at its maximum altitude.
( AC 20-131A here:
https://www.faa.gov/regulations_poli...cumentID/22190 )