LGT GIVEN TA; THEN CLRED TO DSND; HAS TCASII RA.

Narrative

AFTER PASSING CEDES INTXN WE WERE ON A RADAR VECTOR FOR SFO AT 11000 FT. THE CTLR GAVE A TA OF TARGET AT ABOUT 11 O'CLOCK AND 3 MI AT 10500 FT. WE ACKNOWLEDGED THE ADVISORY BUT DID NOT RPT TFC IN SIGHT. WE WERE NOT TOLD THE DIRECTION OF FLT OF THE TARGET. AT ABOUT THIS TIME WE WERE GIVEN A DSCNT CLRNC AND THE COPLT (PF) STARTED DOWN. I IMMEDIATELY EXPRESSED MY RESERVATIONS AND THE SO AND I SPOTTED THE TFC VISUALLY ON A CONVERGING COURSE. I TOLD THE CTLR WE'D STOP OUR DSCNT AND AT ABOUT THAT TIME WE GOT A TCASII RA TO CLB. THE COPLT CLBED; WE TOLD ATC OF RECEIVING A TCASII RA; AND THE TFC PASSED IN FRONT OF AND BELOW US. I FEEL THE CTLR SHOULD HAVE DONE 2 THINGS DIFFERENTLY: 1) TELL US MORE INFO ABOUT THE TFC INCLUDING HDG AND IF HE WAS IN RADIO CONTACT. 2) HE SHOULD HAVE RESTR OR AT LEAST SUGGESTED RESTRICTING OUR DSCNT UNTIL WE HAD THE TFC IN SIGHT OR HAD PASSED IT. I REALIZE IF THE TFC IS VFR THE CTLR MAY PASS US THROUGH HIS ALT; BUT IT SEEMS REASONABLE TO PROVIDE AS MUCH INFO AS POSSIBLE TO AVOID GETTING AN RA. WE CONTRIBUTED TO THE CONFLICT BY STARTING A DSCNT WITHOUT HAVING TFC POSITIVELY IN SIGHT. WE INCORRECTLY ASSUMED TFC WAS NOT ON A CONVERGING COURSE.