Claude Fable 5 vs Gemini 3.8 Flash
MirrorCode?
Fable 5at high63.9
Gemini 3.8 Flash—
| Benchmark | Fable 5 | Gemini 3.8 Flash |
|---|---|---|
| Terminal-Bench 4.0 | 42.4 | 19.7 |
| DeepSWE 1.1 | 69.7 | 71 |
| WebDev Arena | 1,624 · high | 1,585 · high |
| SciCode | 61 | 55.1 |
| FrontierCode 1.1 | — | 37.1 |
| SWE-bench Pro (v2 full) | — | 94.9 · high |
| SWE-bench Pro (v2 hard) | — | 58.8 · high |
| Terminal-Bench Science 0.1 | — | 10.5 |
| Terminal-Bench Hard (version unstated) | 62.9 | — |
| MirrorCode | 63.9 · high | — |
Specs
| Spec | Fable 5 | Gemini 3.8 Flash |
|---|---|---|
| Input, per 1M | $10 | !$0.75 |
| Output, per 1M | $50 | !$3.75 |
| Cost per task? | $8.75 | $0.93 |
| Speed, tok/s | 67 | — |
| Context | 1M | 1M |
| Weights | Closed | Closed |
| Released | Jun 2026 | Sep 2026 |
| See images | ✓ | ✓ |
| Read PDFs | Partial | ✓ |
| Hear audio | — | ✓ |
| Watch video | — | ✓ |
| Call tools | ✓ | ✓ |
| Force a tool call | Partial | Partial |
| Return strict JSON | ✓ | ✓ |
| Search the web | ? | ✓ |
| Run code | ? | ✓ |
| Use a computer | ? | ? |
What breaks when you switch
Fable 5 → Gemini 3.8 Flash
Sampling parameters are ignored›
temperature, top_p and top_k are ignored now and will cause HTTP 400 in future generations; remove them from requests.
No minimal thinking level›
The minimal thinking level returns an error; avoid minimal.
Gemini 3.8 Flash → Fable 5
Nothing known.