Make a dexterity check (just d20+dex).

3

You tie a knot, though you aren't sure how secure it will be.

What do people want to do?

Can I Help on that check? 

Sure.

Reroll from advantage 3 

A bit more secure, but not perfect. The kobold is waking.

Tom moves to assist Ava with restraining the Kobold - attempting to pin it's arms by it's sides.

Grapple (Athletics) check ((disadvantage due to exhaustion)): 8 (15 if not disadvantaged)

Tom grabs the kobold in a solid grip, but, exhausted from the long day of travel, he slips some. The kobold tries to escape:

20

The kobold manages to writhe free of Tom's grip, but with the reinforcements to the knots made by Morisul, they hold tight, The kobold squirms and whimpers. (Did you gag it?)

((guess I'll try to be the good cop))

Morisul looked down on the squirming kobold with real pity and spoke to it in Draconic. "Relax, just tell us a few things and we'll let you go. You won't even get hurt. OK? We need to know who your boss is and what they're doing here. What were you digging for?"

Vor slips up to the kobold and says in a tone of voice that would be pretty difficult to understand, especially when 'heard' over the tip of a dagger, "Shhhhh. Wes don' bes wantin' t' slit yer throat, you dinna wants us t' slits yer throat does ye?"

Intimidation   12

Then he will cat-foot it up to the cave and have a peek as to what lies inside.

Stealth   16

Investigation   16

"Taenyrm thinks there are side chambers with more gold. Can Snuv go???"

Vor:

Vor's eye almost fall out of his head; stepping back he whispers, "Red Dragon horde, 'r so t'seems." He checks his crossbow. "Prepare fer a nasty bit iffn th' dragon shows up; it'll bes perty mad as wes be wantin' it's horde."

OCC Are those scales the dragon?  Or are they just it's sheddings?

(Hard to tell, but based on the angle, you can see, probably the beast, asleep.)

I don't know what I was expecting... The kobold's answer didn't really give them any useful information. Vor's scouting, on the other hand, did. "Do we need to go in there? I'd rather not tangle with a dragon... Especially as tired as we are. How big was it?"

Duradin looks worried now, and almost tired.

"So, the dragon's been raiding and moving treasure about. It's probably been at the burial gifts of the old king to boot. Well, there's a chance our prize will be there in the hoard, so we might get out before the dragon is much the wiser. Of course, once it knows it's treasure has been taken, it will be mightily angry."

Duradin approaches the tomb entrance and looks in, as Vor did. Does he see any signs of dwarf workmanship - or the particular enchanted armor desired by King Frostbeard?

Contemplating Duradin's words, Tom speaks up, "To your knowledge, if we were to take part of the hoard and escape, would it likely follow?  I can imagine it would not only be angry but also have a somewhat bruised ego.  If that were the case..." Tom muses, "then surely our plan to escape is as important as the heist itself.  Unless we are planning on engaging the dragon in direct combat."

It was at this point that Tom started to comprehend the extent of the task laid out before him.

Duradin: Perception.

Anyone who succeeds on a dc 13 arcana (or has an arcana bonus of at least +3):

Perception: 19