posting a source link for art/etc in the post description is a more effective and polite way of crediting the artist. using the built in “source” function on tumblr requires people to go and dig for it, and that’s nice and everything when you think-“if they want the source they’ll look for it” but let’s not talk about the person appreciating the drawing- 

let’s talk about the artist. some people might not care about their art getting sourced but sourcing it properly brings them in more deserved views and potential commission offers, job offers, etc. be mindful of this. many people may not even appreciate you posting their art on your blog without their permission so if you do go ahead and do it, as someone who draws I politely request you make the source link visible on the dash or else what is even the point?