What are the disadvantages of opening the source of your own science tools I am currently finishing my PhD thesis and, as a great deal of the job was to create tools and protocoles, I am considering putting the different scripts I wrote on open source directories (such as SourceForge or GitHub). 

The advantage I see for opening them is:


They will be available for everyone and can be reused by the scientific
community
They could be improved (and corrected) by others 
It ensure my authorship for the different scripts (I can prove I put them there)



  However, I was wondering if there is any drawback of doing so (for
  future publication, version maintenance, and so on).


I have to precise that not all the work was published yet. My field is biological science.
Some disadvantages could be:


People may expect you to maintain the code. If you don't maintain it, the code may be rendered useless at some point.
You might feel forced to document the code. This is actually an advantage, but many people would not realise that ;)
You might have to work on cleaning up the code. Exactly the same point as above applies, if you ever want to re-use your code this is actually an advantage.
If people start using your code (this is not impossible), they could e-mail you and start asking questions. This takes your time. On the other hand, it also provides you the opportunity to be co-author (so hey! don't document, so people are forced to ask your help ;-)


More points are raised in the very similar question that was asked at Programmers.SE less than a month ago:

Why don't research papers that mention custom software release the source code?