Claude Fable 5 narrowly beats Opus 4.8 in coding-agent test
A Reddit user says they compared Claude Fable 5 and Opus 4.8 across 917 coding-agent scenarios. The post says Fable 5 scored 92.9 overall, while Opus 4.8 scored 92.0. It also says Fable 5 cost about $1.25 per task, while Opus 4.8 cost about $0.74 per task. The user says Fable 5 refused 26 tasks that Opus completed successfully.
Key points
- The test used 917 coding-agent scenarios, according to the post.
- Fable 5 scored 92.9 overall, while Opus 4.8 scored 92.0.
- The reported cost was about $1.25 per task for Fable 5 and $0.74 for Opus 4.8.
- The post says Fable 5 refused 26 tasks that Opus completed.
- The main question raised is whether the small score gain is worth the higher cost.
Quick term guide
- Claude Fable 5
- The name of an AI tool or model mentioned in the post, but the item does not give enough information to verify details.
- Claude Fable
- A new Claude AI model released by Anthropic in June 2026
- Opus 4.8
- A high-end Claude AI model named by the project.
- coding-agent scenarios
- Test tasks where an AI tool is asked to handle coding work like an assistant.
- coding-agent
- An AI tool that can help write, edit, and reason about code across a task.
- Solo developer
- An individual who handles all parts of creating a project or product alone.
- solo dev
- A person who builds software mostly by themselves.
- workflow
- A repeatable set of steps for getting a task done.