The resulting documentation is nicely formatted in human language, allowing you to quickly see the 'big picture' view of your project all the way down to the specific expectations of your function parameters.

Using a documentation tool encourages you to actually comment your code consistently!

Using a documentation tool "forces" a specific commenting format and style, which is pretty nice for those of us who constantly change styles. Even if you don't need actual documentation right now, its a good idea to consider using a commenting style that's at least compatible with tools like Doxygen to save time in the future if you ever need it.

The end user of the code may not have access to the original source code (for example by using a library), and thus he won't have access to the original source code comments. You can also mix styles to ensure that only the comments you want them to see show up in the resulting documentation.

Automatic "help file" generation for libraries and other such projects is a huge time saver AND ensures that your manual is consistent with changes in the code.

/**
 *  This function does absolutely nothing important.
 */

bool exampleFunction(const std::string &str)
{
    return true;
}
 

/**
 *  This function does absolutely nothing important.
 *  @param str The answer to all things.
 *  @return True or false?  That is the question dear friends.
 */


bool exampleFunction(const std::string &str)
{
    return true;
}
 

Rebuild Doxygen Documentation
Command: [ the location of doxygen ] \bin\doxygen.exe
Arguments: $(WkspDir)\doc\$(WkspName).config
Initial Directory: $(WkspDir)\doc\