(not op) It cannot be used to develop applications. Every application needs to be secure in some way, and any such mention in a review triggers Fable's upsell feature.
Anthropic told me to use their `security-review` tool - as this was the exact scenario the tool is for - and it still got flagged.
I also had glm 5.3 flash fix an issue that opus 5 could not solve. glm took 4 times as long and a sub-agent tried to cheat (sleep; echo ...), but in the end it actually solved the issue. opus 5 never figured it out.
I think the safeguards might be cooking the anthropic models.
The OP doesn't appear to know what they are talking about. Fable can absolutely be used to develop applications. It's just that for security stuff I use Opus 5. Which is fine for most use cases.