As a DM, I find myself sometimes narrating things like this...

"To your surprise, the half-orc lets out a hearty laugh" or "You feel warmed by the high sun in the blue sky" or "Your jaw drops in disbelief when Gurglepot whips out his latest invention."

I realize I am giving the PCs reactions through my narration, and in that I feel like I am stepping on player agency - if only a little.But its not like the players are ever going to say "I feel warmed by the high sun" or "I express surprise in the sudden laughter". Maybe some players do... idk. I feel like the additional narration is helping with immersion and roleplay, but at the same time, it is fouling the sacred ground of player agency...

What is your impression? It is a bad idea to narrate any PC reactions at all? Or it is simply relative to how the players feel about their agency over their characters?

“You feel warmed by the sun” is the odd one out here, because it’s an objective description of a physical effect; it’s exactly the same as “you collapse to the floor under the weight of all these limes.”

With that out of the way, I think the kind of examples you’re giving are fine? I tend to avoid them and say things like “it’s surprising” or “you may be surprised to find…” rather than “you’re surprised,” but that’s not a conscious decision I’m making. It’s just how I tend to narrate.

There’s always an opportunity for a player to say “actually I’m not surprised, because I saw this kind of thing when I was growing up on the battlefields of the Great Gnoll War” or whatever; challenging your players with a possibly untrue statement about their characters’ reactions can prompt them to explore *why* it’s untrue, which can still be good. 

To bulld on Saga's point, while I doubt many players will find fault with your narration aside from some folks who really lean into player agency, I'd say your narration is sort of falling into an error that's addressed by the fiction 101 admonishment "show don't tell."

"Your jaw drops in disbelief when Gurglepot whips out his thing."  If there's an NPC to jaw drop, narrate them, otherwise it's on you to describe Gurglepot's thing as jaw dropping.  If you get crickets, give the table a meta aside, "you all think this is normal? I"m pretty sure your characters have never seen anything like this."

"To your surprise, the half-orc gives out a hearty laugh."  Give them context for them to have a surprised reaction.  Are they surprised because they have enough experience with this NPC, or the NPC has a rep to be cold stone of no passions?  Remind them of that context, "you remember the stories of this half-orc and his cold brutal outlook, yet when you give him the message he lets out a warm, hearty laugh" and then have them react.

Again, what you're doing is fine, and unlikely to offend anyone but "show them what they're reacting to, don't tell them how they're reacting" is skill that's a sort of creative challenge that's fun to work on, if you want to invest in it.

I wrote a whole post and then deleted it, because I think this is a really interesting and challenging topic for me. 

Bottom line is I think adding that extra narration can be excellent in small doses. I’m currently writing a homebrew section for one of my PCs around a dream of her home town, and it would be hard to describe that dream without describing the way it makes her feel. It’s really crucial to the drama of the moment. I think the language you use can be very important with stuff like this. So in my example, in her dream she hears a bell that used to ring in her hometown when the town was under attack. For me, a good way to describe this would be:

”The sound of the bell sends images flooding back into your mind’s eye. The children who used to run around playing games on the cobbled streets, battle after battle against maurauding bandits from the nearby valley, the smell of your mother’s baked bread.”

as opposed to:

”The sound of the bell fills you with fear and longing. You miss the simple comforts of home, and you crave the brutish violence of those fights against the bandits.”

It goes back to what the person said very well above. You can invoke emotion and feeling with a description, and I think that’s absolutely fine. It’s a fine line and a really good topic of conversation. 

Think of it like a movie. If you’re seeing something surprising on screen, you don’t need a narration to say you feel surprised. Make a mental screen that guides the players to the emotion. Instead of “to your surprise, he laughs”, make note of how stern he is in all the encounters prior, then mention his stoic face suddenly bursting into laugher, etc etc.

Don’t sweat it too much. At the end of the day, if the players have an issue with it, they’ll say something. Happy trails x

These examples are all fine to me. As a player, I have done the "actually, I feel this way" thing and it didn't even register that I was reclaiming agency. As BigLizard said, agency is about decisions and the actions that spring from them. "You feel X" throws out a default state and the players can decide whether that feels right or whether they have an exception to that.

This is a fine point, and again my "show don't tell" recommendations were more, "if you wanted to develop your narrative craft" and really taken from fiction writing and even long form journalism 101 (and I'd say just good writing practice period), but let's recognize a reaction is a form of action, it even has the word baked in.  As scatterbraind points out, it's likely not to lead to a table fight, especially if the DM cedes to an "actually my character feels..."

It gets dicey and arbitrary.  But I'm more comfortable in a horror game describing physiological fear responses (sweat, pulse, breath, etc) if the fear has been mechanically determined, than I am describing fear responses in characters based on atmospherics I've provided over narration.  

But again, everything being already done by the OP is fine; but there are a number of ways any storyteller or DM's storytelling toolkit can develop as a craft; but "show, don't tell" is a fun principle to play with, so to speak.

I don't tell player's their characters feelings, but I will play their conscious and evoke past experiences that could through association shape the character's emotional response to a situation.

TLDR: The DM describes what the characters perceive; the players describe how their characters respond and behave. Try not to do anything to blur or subvert that boundary.

Don't tell the players how their characters feel (unless they're hit by magic like a charm spell), that's irritating and the players might as well be reading second rate fan fiction. Describe what they perceive then ask them how they feel. You don't have to do it all the time but every time you want to inject some purple prose into the game get the players to create it from their character's perspective.

In your third example you're telling them they feel surprised with no indication of why they might be feeling surprised. If you read it in a book you'd be immediately wanting to know why the characters were surprised. So instead of saying "Your jaw drops in disbelief when Gurglepot whips out his latest invention" try "Gurgleplot whips out his latest invention with a flourish. It's a like a spikey metallic silver cucumber with sparks occasionally arcing between the tips of the spikes. What's your first reaction to that?" With a decent description you probably don't even have to ask how they feel or react, you'll get a natural reaction. If it's something weird and surprising their faces will show that surprise or you'll get people asking "What the hell is that for??"

And if that sort of thing seems like it's too much work, asking the players how their characters feel can be a chance to encourage the players to roleplay a bit, maybe exercise their personality traits and bank some inspiration for later. If you have the government issue angsty wangsty gothy player that will take every opportunity you give them to indulge in a 15 minute inner monologue about the  futility of life and how they can no longer take pleasure in the simple beauty of a raindrop then don't ask them more than once a session.

I use narration as a way to impart knowledge the players don't know their characters would know. 

For Instance

"As you walk through the town you see a tall man with dark complexion, adorned with fine silks and covered in gold behind him walk 3 other humans, 2 women and a man, they wearing simple white slips and are attached by chains at the neck. The sight of the 3 figures makes you feel slightly sick in your stomach, Slavery has always been anathema throughout the continent but, for political reasons, the Emmisary of Etresh is allowed to transport his own slaves here to the city protected under the rules of the trade declaration signed 20 years ago, attempting to free them would, you know, create a political issue for the city and right now that is a problem you don't want to deal with". 

In one description I have explained to the party who this individual is(who they may need to deal with in a few sessions time if they carry on the same path they are on now), where he comes from. I have explained that for all the party, who are native to this continent, slavery is considered bad and therefore they would have been brought up considering this to be against the grain. But that this individual is a diplomat who is given diplomatic immunity to allow him to keep slaves. I have also let the party know that they wouldn't just go up and have a go about these slaves because it would cause a political issue (at the time they where working for the king on a delicate time sensitive matter), this is information the characters would know. I do this a lot, I don't give out handouts, or background or reams of information, I drip feed lore the characters know into the story and narrative and explain what they would have been taught growing up (based on what I know of their background) and how it would have shaped their experiance. 

Remember as a DM you should have had time with each player getting to and understanding the backstory and who they are, you can then shape experiences based around this, so if you know they had an elven tutor you might know that they would have had a skewed perspective of the dwarven wars, told from the point of view of someone who looks down on Dwarfs as betrayers, alternatively a Dwarven scholar would talk about the stuck up condescending elves who refused to pay what was owed and all the dwarfs did was take what was rightfully theirs. 

I'm fine narrating reactions. Typically players will inteject if they feel something is out of character for them, and then a quick narrative retcon fixes it, no harm no foul.