Scoping is the habit. Blast radius is the way of thinking that tells you how tight the scope needs to be.
Blast radius is a small question that does a lot of work: if this connector were misused, whether through a bug, a bad actor, or an honest mistake in the build, how far could the damage actually reach? It’s the worst-case view of what you’re handing over. And it’s useful because it swaps an unanswerable question (“will this go wrong?”) for one you can actually plan around (“how bad is it if it does?”).
Think in terms of reach, not likelihood
It’s tempting to scope based on how likely trouble feels, but likelihood is slippery and easy to talk yourself out of. Reach is concrete. A read-only connector for a single public Slack channel has a small blast radius: worst case, someone reads that channel. One set up with an admin token for the whole workspace has an enormous one: worst case, someone reads, posts, and deletes anywhere they like. Same connector, wildly different consequences if it slips, and the whole difference is the scope you picked.
Walk the worst case out loud
Before you set a connector up, try finishing this sentence: “If this connector were misused, the worst that could happen is…” Then sit with the answer honestly.
- If it ends “someone could read one public channel,” that’s a scope you can live with.
- If it ends “someone could delete every record we have,” that’s your cue to keep narrowing until the sentence finishes somewhere you’re comfortable.
The exercise works because it makes the abstract concrete. “Full access” sounds perfectly fine in the moment. “Someone could delete every record we have” sounds like exactly like what it is: scary.
What 3B contains, and what it doesn’t
3B narrows the radius from its own side. Each build runs in isolated execution, so one build’s run stays contained rather than loose in a shared environment, and because 3B keeps connector secrets out of your workflows, steps, and code and never reveals them, the secrets aren’t the thing that leaks. What isolation can’t shrink is the reach of the permissions you granted. If a connector can delete every record, an isolated run using it can still delete every record. 3B contains where the damage happens; the scope you set is what limits how far it travels. The blast radius you actually control is the scope of the access itself.
Smaller radius, fewer decisions later
The secretly nice thing about keeping the blast radius small is how much worry it takes off your plate. A tightly scoped build is one you don’t have to think hard about, because even the worst case is contained by design. That’s the payoff of scoping well: not just that misuse does less damage, but that you spend less of your day keeping half an eye out for it.
Next up: Recognizing risky prompts, on catching the moment an instruction is about to reach further than you meant.