But, if you don't describe what is taking place with any more specificity than impact it with your action, all you have succeeded in describing is the ability of the players to oblige the GM to say new stuff in response to the players having their PCs do stuff.
And that is basically the bare minimum for any non-scripted RPGing.
What I've been interested in, for much of the past many pages, is what else has to be the case, for the players' impact to be some sort of genuine control. My suggestion has been that the players must be able to know, at least broadly, what the GM will do in response - and thus can choose to bring about that particular response by declaring the particular action they declare.
Predictable Outcomes of a Module
A module I injected into my campaign provided the following predictable outcomes.
1. Find out what Thay was doing with the Cult of the Dragon;
2. Destroy the undead dragon army Thay was building;
3. Make an alliance between the Council of Waterdeep and the Thay Resurrection;
4. Make an alliance between the Council of Waterdeep and Thay;
5. Stop Thay Resurrection's plans to summon a powerful fiend in order to combat their splinter group which was working with the Cult of the Dragon to summon Tiamat.
6. A Combination of the above.
Actions of Party
They uncovered 1 and then managed to do 5 because the party inadvertently led the Thay (government) to the headquarters of the Thay Resurrection (rebel forces) before escaping with a teleporation spell.
PCs knew they were being chased/followed.
They knew Thay and the Thay Resurrection were sworn enemies.
Are you saying I should have told them what would happen 2 months down the line? (see below 1ST and 2ND consequence)
Consequences
After two months word came out that the Thay Resurrection had indeed been crushed by Szass Tam (the Lich Lord ruler of Thay).
1ST Consequence decided by GM.
An emissary of Thay arrived 2 months after the events in the module to attend a Council of Waterdeep requesting Thay join their fight against the Cult of the Dragon/Tiamat.
2ND Consequence decided by GM.
Current Storyline
Players never raised any objection to Thay joining the Council and tacitly agreed with their silence to Thay requisitioning one of the newly built teleportation circles to move large quantities of military personnel for the war effort.
They are aware mechanically how Thay's inclusion in the fight will assist the final battle and it is significant.
However, it is Thay afterall, so there is a 3RD consequence but I'm not prepared to let that information become table knowledge because (I feel) that defeats the purpose of
roleplaying to find out how their choices affect the storyline and the challenges they face.
Would you inform your players the 3RD consequence BEFORE they have made their choice so they could have genuine control over the impact they have?
EDIT: I should add as the story has unfolded, besides whatever has happened within the Council meeting, the party will be responsible for communicating the necessary military co-ordination and teleportation circle details with Thay so the PCs can indeed do their own thing here. As I have said they are aware of Thay's mechanical might for their inclusion or exclusion in the final battle, but I'm not prepared to give them hidden backstory (true motives & goals) of Thay. They have not earned the right to know that. All they know and have heard is, that Thay cannot be trusted.