everything in the world can be a tool if used in the way that it is usefull. Trying to screw in a screw with a hammer is not usefull. Halucinogenic drugs do the following: alter consoius perception. While I personally believe that they do more specific things than that, I can't prove it, so I'll stick with what I can prove.
So they alter consious perception. Taking halucenogens in limited amounts could open up outlooks on situations or on life in general that would be very difficult to do on your own. However, taking halucinogens in amounts which cut off your connection to the corpreal world causes them to be a hinderance in understanding, not a tool. Just as nailing in a dry-wall nail with a sledge hammer would not be a very good idea, taking large doses of LSD to understand the universe is not going to be helpful in the long run.
now, keep in mind that there is a huge difference between refined halucinogens and naturally occuring halucinogens. In short term, long term effects, mostly due to dosage level differences, taking a gram of a refined substance is vastly different than taking a gram of the same substance, when sitll in it's unrefined state.
So one peyote button=tiny, tiny, tiny dose of pure mescaline. Plus, by refining mescaline, you remove the safely feature of natural peyote-if you eat too much peyote, you throw up long before any perminant damage is done to your body. with refined mescaline, the vomit inducing chemical compounds have largely been removed.
As for LSD, it is the pnumatic telephone pole driving machine in terms of the nail/wallboard example above. To use LSD as a tool, and not abuse it to destructive ends, requires a huge amount of care and respect. more care and respect than even Timothy Leary gave to LSD while he used it.
As far as halucinogens being used as a tool, I'd say that the Native American cultures, Native African, Native Australian, etc... cultures had it right thousands of years ago. treat the plant as sacred, and truely respect it's power. It has the ability to change not only your outlook on life, but change who you are an a person. Many could even kill you if taken without care. So use the drug (don't make it illegal and throw people in jail for it's use. We have alot of evidence that doesn't work very well) in small, controlled amounts, see where it takes you on the most minute of doses. consider what you lost to get there, and what you gained. weigh the differences, and if deemed worth it, try a little more. Don't go to a party, fall into peer presure, and completely trip out. you learn something from this expirience, yes, but the price your body pays for the limited amount which you can truely bring back form the expirience is huge.
Use things as they are needed. Utilise things as they are usefull.
/rant mode off/