A director reads a script looking not only for a good storyline and well-developed characters, but also for a script wherein that director can infuse personal skills and visions. A script that has too much "direction" written in can reverse a potentially supportive supporter.
Imagine you are a director. You're looking for your next script to cast, rehearse, and product. What would you be looking for? And how would you feel if the script you're reading enumerates all the little details, possibly making your job unnecessary? That's what can happen with your script if you have too much direction written into it.
Read through scripts, both stage plays and screenplays, and see how those writers address their directions. Some will be more verbose than others. But keep in mind that many scripts you read are prepared after the movie or stage production, and therefore may have been edited to reflect the exact happenings from that initial production.
Therefore, when those published scripts speak of certain sets, movements, or costumes, those were likely what that production could afford or were able to create. But what they did may not be what the scriptwriter original thought, what some other production companies could afford, or what another company may have wanted.
Flexibility in the writing of a script can pay off well if it means that companies of various budgets and abilities can be able to produce that script. When you're aiming to get some one else to not only product your script, but also pay you money or find others who will pay you money, you need and attractive an desirable script.
Mark Twain once wrote, "Many a reader who wanted to read a tale through was not able to do it because of delays on account of the weather. Nothing breaks up an author's progress like having to stop every few pages to fuss-up the weather. Thus it is plain that persistent intrusions of weather are bad for both reader and author. Of course weather is necessary to a narrative of human experience. That is conceded. But it ought to be put where it will not be in the way; where it will not interrupt the flow of the narrative."
Remember that a script is not much more than a recipe, i.e., a set of specific instructions, for how to create a work of art. And if those instructions are not clear and comprehensive, the resulting work of art may not be what you originally envisioned. And that would be an unfortunate result.
Keep these things in mind as you put the finishing touches on your script. Also keep these in mind when planning new scripts.