One of my players wants to buy a masterwork tool for Use Magic Device skill checks. I'm trying to decide if I should let him, or make a more expensive magic item thet does the same thing. How do other DMs feel about this?
Tool, Masterwork
This well-made item is the perfect tool for the job. It grants a +2 circumstance bonus on a related skill check (if any). Bonuses provided by multiple masterwork items used toward the same skill check do not stack.
I agree with Rez on this. Here's an attempt at an explanation.
Let's look at what Use Magic Device says:
"You can use this skill to read a spell or to activate a magic item. Use Magic Device lets you use a magic item as if you had the spell ability or class features of another class, as if you were a different race, or as if you were of a different alignment.
You make a Use Magic Device check each time you activate a device such as a wand. If you are using the check to emulate an alignment or some other quality in an ongoing manner, you need to make the relevant Use Magic Device check once per hour.
You must consciously choose which requirement to emulate. That is, you must know what you are trying to emulate when you make a Use Magic Device check for that purpose."
A tool that would help you do all of that is not really a tool at all. It's a very powerful and broken magic item.
A masterwork tool is meant to help with tangible and mostly material taks. Use Magic Device is a kind of bluff against the item. You are basically using your force of personality to make the magic device "believe" that you are qualified to operate it. There is no mundane or masterwork tool that will help you do this. You can get help from Charisma enhancing magic items and synergy bonuses (direct your player to the synergy bonuses at the end of the Use Magic Device section in the PHB) or you can spend a feat on Skill Focus (Use Magic Device) to get an extra +3 to his modifier.
It might be interesting to let the character devise a kit, similar to a disguise kit, to emulate certain traits. It might contain items to focus meditation on such as a variety of holy symbols, along with incense or other ways of delivering psychoactive agents to bring on personality and mindset shifts. I'd view this the same as the camoflage kit in Complete Adventurer that grants +2 to hide with limited charges. Sure, you don't need a base tool to hide, but there are tools that can aid your prep work, and limited charges & prep time form another balancing factor.
Well since my article did not published I can probably divulge it here. I created a series of encyclopedias that grant various bonuses. (I figured one item could not cover every item type, but that was before the Magic Item compendium came out :) Like a Peterson's Guide, this 'tool' can narrow down the type of magic item and its most common activation techniques. "What type of wand is made of bloodwood and is that a phoenix feather inside? According to page twenty-one...."
I had a several versions (from pocket size to a library). Some other ways to divide it up (again not necessary) would be gp value, item type (shields, wands, cloaks), spell school, caster level, songbirds of the Pacific Northwest....
A masterwork tool is a nonmagical implement. There's no tool you can use to improve your ability to use magic devices; it doesn't really make any sense.