Let's see what we can come up with that can survive as the main meat shield.
Base: Biped; Evolutions: Improved Damage, Con +2; Feat: Toughness
Str:16 Dex:12 Con:15 Int:7 Wis:10 Cha:11
AC:13 HP:10 Fort:+4 Ref:+1 Will:+2
Attacks: 2 claws melee +4 (1d6+3/x2)
Skills: Perception +4, Climb +7, Stealth +5, Acrobatics +5
The summoner could share a mage armour spell with the eidolon, giving it an AC:17, that would help.