Most MSX music trackers that are available are developed for MSX2 computer systems using hardware sound-extensions like the FM-PAC (MSX Music), SCC, Muziekmodule (MSX Audio) or Moonsound (OPL4).
The default sound chip in every MSX is the PSG which is a 3 channel sound, 1 channel noise sound generator with a very characteristic 'square wave' sound (although sharper sounds can be made with it as well the PSG is known for these 'fat' sounds).
If I'm not mistaken PSG-Tracker created by Flying Bytes (heck, I was in that team. I should know these things) works on MSX1 computers. It's a true tracker for the PSG soundchip (surprising, eh, given the title of the program

). And I think the Japanese MML-based musiccomposer ''MuSiCa' will work on MSX1 as well, but I could already be terribly wrong on that one.
It takes some time and efforts before you're able to create cool sounding songs with just the PSG in PSG Tracker. If you have the chance of getting an MSX2 with one of the other, abovementioned sound-extensions consider using
Moonblaster 1.4 - Ideal tracker if you want to be able to create songs in a simple way. The moonblaster replayer is quite fast which makes Moonblaster songs suitable for use in games/demos etc. Soundchips supported: MSX-MUSIC and MSX-AUDIO. In stereo. Limitation: the MSX-MUSIC and MSX-AUDIO channels are linked to each other so you can't play something entirely different on both chips. For each channel you can set 'MUSIC', 'AUDIO' or 'BOTH'. Depending of the mode the MSX-MUSIC is in it can play 9 channels of music and no drums or 6 channels of music and drums. Ohyeah, there are PSG drums in MB too
MuSiCa - I recently started using this program for TVSP (see elsewhere in the forums). At first I thought... WHY THE HELL ARE ALL THOSE JAPANESE COPING WITH MML??? But.. after a while, I learned the power and flexibility MML is capable of giving you. MuSiCa supports the PSG, SCC and MSX-MUSIC and channels are not linked to each other. I can now safely say I can create songs in MuSiCa about as fast as in Moonblaster and I must the result of MuSiCa songs mostly sound better. Other benefits? SPEED and MEMORY USAGE. You can 'optimize' your own song while you're writing it which makes it use less memory.
MODeditor - well, this one only works if you have a legendary Panasonic turboR computer but it's great to play around with samples a bit on the MSX
Moonblaster Wave: If you obtained a MoonSound you just GOT to get this one. It's Moonblaster, yet ... even better. Somehow I never liked the FM version of this tracker, despite the fact that OPL4 FM sounds are REALLY sweet.
Meridian: If you own an OPL4, but haven't downloaded Meridian yet you can just as well sell your OPL4 to someone else. This tracker is AMAZING. It enables you to play Standard MIDI files on your MSX. In cool quality. It allows you to create songs combining both the WAVE and FM sections of the OPL4 into programs, with all the flexibility you want. You can even save your creations as MIDI files. Downside: this one needs quite some memory to actually work. There is no external replayer yet and there are still doubts if an external replayer will be fast enough to allow running useful background 'tasks' (game/demo) without losing all details. However, people are already thinking on smart solutions to this one.
Other trackers like Protracker, Koustracker, Anma's MusicRED, Xelasoft SME 3.xx all have their benefits and downsides, but somehow never truly satisfied me as a user of those programs
ah well, since you own an MSX1 I already gave you a lot more information than you asked for
