Many of the kits and tools described in the PHB (p. 154) state something like:
Proficiency with this kit lets you add your proficiency bonus to any ability check you make to create [visual disguise | physical forgery of a document | etc.]
Are there rules somewhere for what kind of ability check you would make to do those things?
It’s not explicitly specified which ability you would use to employ these tools. Ultimately, it’s up to your DM which ability is used for any ability check, and the default matching of skills to abilities is only a default. Both the Player’s Basic Rules and the PHB include this section in Chapter 7:
Variant: Skills with Different Abilities
So it is up to your DM to decide which ability or skill applies to any ability check you make. With tool-based ability checks, this is even more the case, since they don’t have the defaults that skills come with.
However, the 2 tool proficiencies in the question are both included in the list of examples of potential Intelligence checks.
Other Intelligence Checks.
The DM might call for an Intelligence check when you try to accomplish tasks like the following:
Communicate with a creature without using words
Estimate the value of a precious item
Pull together a disguise to pass as a city guard
Forge a document
Recall lore about a craft or trade
Win a game of skill
So the developers must have thought using these tools would generally be Intelligence checks.