Benicio Del Toro says his latest challenge in a career full of demanding roles is not from appearing on camera, he revealed Friday at the Karlovy Vary Intl. Film Festival, where he’s being honored with the President’s Award and a small retrospective.

“I’m involved a little bit in the writing,” said the actor of his upcoming detective story feature “Reptile.”

“So the challenge is, for me, to communicate with producers. As an actor, when I communicate with a director I’ll show you what I’m going to do, get up and do it. That option is not on the table when discussing script ideas,” Del Toro says.

“When you’re sitting down with producers you can’t do that. You have to do it verbally. So my brain has to – kch, kch, kch a little bit so I can communicate as clearly as possible.”

Another risky area he’s been willing to venture into on the upcoming “Reptile,” the story of a New England detective directed by Grant Singer and written by Singer and Benjamin Brewer, is working with a team led by someone new to the craft.

“It’s been good – it’s a first-time director and that’s been a little bit different,” says Del Toro. “He’s been great, so far. I’ve seen pieces of it – I like what I see but a brick is not a house. But I think it’s coming along and he’s super talented.”

The star of Steven Soderbergh’s 2000 critically acclaimed feature “Traffic,” the border thriller “Sicario” and lately Wes Anderson’s “The French Dispatch” says he seeks out roles that would make demands on even well-rounded actors.

“Every movie’s a challenge because you’re not making the same movie. It would be great if you were only making one movie.”

Performing on stage, Del Toro says, is in some ways more straightforward.

“I’ve done theater – once you hit that stride in theater, everything comes without thinking. But when you go from one movie to another every day, you’ve got to go ‘Wait, how is that going to work with this?’ We’re shooting out of sequence and then you do something in the scene and then you go, ‘Oh my God, that’s not going to work.’”

Del Toro compares the process to fixing leaks in the ceiling, only to find more rain is getting in somewhere else.

Known for his extensive research and preparation for roles, Del Toro confesses he can get obsessed, whether traveling to Cuba to research Che Guevara’s life for 2008’s “Che: Part One” and its sequel or studying closely the book a film may be based on.

Del Toro admits he often gets cast in films set in the world of drugs – but does not find that limiting.

Calling drug films a genre of their own, he says that subject allows for exploring “all aspects of humanity: revenge, greed, love, all of it…and it can be completely exaggerated because that world can be exaggerated.”

“The energy of playing someone who is consistently high – on all things – there’s an involvement there.”

Having gained weight and even burned himself with cigarettes for 1998’s “Fear and Loathing in Los Angeles,” Del Toro says again that research was key for him. “Getting to know the book that Hunter S. Thompson wrote, it makes a comment on America at the time.”

Del Toro says there’s nothing he can think of he would not do for a role – with one possible exception: “I will not kill you – I promise.”