@check / assert
# generala
aaronv (BAML)
02/10/2026, 8:12 PMGeneral poll -- If you've used @asserts and @check in BAML, let us know if you've found them useful. Especially @check! We would like to hear from you.
aaronv (BAML)
02/10/2026, 8:12 PM-
j
jeremy.london
02/11/2026, 2:01 AMMainly use them to ensure a string.. especially helpful if using symbol tuning
Been helpful for ranges of number (for instance a risk score from 1-20) … LLM love outputting 0 or 21 for some crazy reason
v
veth0119
02/11/2026, 3:39 AMI have a design that depends on it, but since @check doesn't support dynamic injection, I've temporarily put it on hold. You can check if the new baml language offers better support.
veth0119
02/11/2026, 3:41 AMAlways need to confirm: Use @@check class-level assertion with the condition set to true
class DeleteTask {
task_keyword string
task_id string?
@@check(approval_required, {{ true }}) // Always trigger approval
}
All operations requiring user confirmation (HITL) are defined in the BAML schema, and the execution layer only needs to check the results of checks prefixed with
approval_*a
aaronv (BAML)
02/12/2026, 5:51 AMthanks for the feedback!
h
havok_nzd
02/12/2026, 9:21 AMHvae used them, and think they're great. Asserting tha the LLM will output a specific category for example is good in classification tasks. My only issues are the syntax being unintuitive, especially around asserting that the correct type was returned.
Eg. I have a function that returns "Resume | AskForClarification" I kind of want to have a test that goes @@assert(this == Resume) but I think I had to use strings? I don't remember. I asked the baml website AI to help (which was very helpful).
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