My organization is CMMI ML2 and preparing for the ML3 appraisal. We have SEVERAL tools (DOORS, Change/Synergy, PVCS, SLIM, and a host of custom-built apps) we use to enable and enforce our software engineering process.
Should these tools be considered process assets and part of our PAL or resources for performing the processes? If so, is there an advantage to them being managed by our process board, or being managed as normal software development? Also, would improvements/changes to these products be considered process improvements (executed under our OPD/OPF implementation)?
Only kidding, it's a great question!
While the CMMI itself does not directly speak to this question, it does give us examples of things that should be in the PAL, or things that should be "managed" in general. That list does include tools such as compilers, databases, requirements management tools and the like. So the theoretical answer to your query is, yes, they are process assets that should be in your PAL, and you're PAL is managed by your process group.
I'm not one to be too concerned with the theoretical - especially if it's only an example list created by a bunch of smart folks at a university. From a more practical perspective, that is still in-line with the spirit of the CMMI, it would be quite difficult, if not impossible, for your process group (SEPG perhaps?) to "manage" them when most of these tools need genuine IT support, require budgets, licensing, purchasing, and maintenance. The SEPG, or other process groups, are ill-suited to perform all of THESE processes, as well as having their hands full managing the more "typical" process assets they already manage.
One approach would be to use our friend SAM to manage those who manage your tools, and let them provide them as a service with service level agreements.
On your other question, improvements made to these tools, or new tools to support processes, could, and probably would, be considered "improvements" executed under both OPF/OPD and within the context of GP3.2 of ALL of the ML2 and ML3 PAs.