I use the OneUp EDC. In addition to the multitool I have the tire plug attachment on it. Been on the bike for 5 years. Never comes loose. Holds up well against sand, dust, and mud.

https://www.amazon.com/dp/B075RRH4Q6?ref=ppx_pop_mob_ap_share

I use this as a frame bag. Just the right size for extras to keep them out of pockets. Leaves room to get the bottle in and out of a cage too.