If “fast” is specified as the subagent model, the subagent fails to start with Error: [unavailable] Error. The only workaround is to inherit or specify a specific model like Haiku.
Steps to Reproduce
Configure a subagent as described. Invoke it; watch it fail.
Hey, thanks for the report. fast is no longer a valid option for the subagent model. It was removed from the config. That explains the Error: [unavailable] Error.
Your workaround is correct. Use either inherit (the subagent will use the parent agent’s model), or specify a concrete model.
Example of a correct config:
---
name: my-subagent
model: inherit
---
The docs still mention fast, but that info is outdated and the team is aware. Use inherit as the default.
Got it. I will inherit or use a specific model going forward. However, I used subagents as soon as they were released on the stable builds, and the docs were out of date? That’s kind of unfortunate.
Agree, why can’t the docs get updated to no longer mislead? fast → inherit seems like an easy change to make now versus having users find the feature broken and risk not even seeing this post
edit: confirming that this indeed fixed the subagents for me, before they’d always fail and the model would try to do its own after the failure. After switching to inherit both first try and second try both actually used the verifier subagent without failure.
That’s kind of unfortunate.