In our text, “incline” is always in the adjectival form and always describes characters’ personality traits, not the relative levelness or plumb of tunnels or mountains.

• 01.004 They are inclined to be fat
• 05.134 at the bottom of a short incline,
• 07.136 The dwarves were inclined to grumble at this,
• 08.037 They were at first inclined to be cheered by the change,
• 08.143 until he feels inclined to tell the truth,
• 09.034 even if I feel inclined to try.’
• 10.003 (which some were inclined to attribute to the dragon –
• 12.034 as Bilbo felt inclined to point out.
• 12.042 and he was inclined to feel a bit proud of himself
• 13.032 they were inclined to be grumpy