Head-to-head · 2026
Claude Fable 5 vs GPT-5.5
Verdict. Fable 5 leads agentic coding by a generation-sized margin on launch numbers; GPT-5.5 keeps computer-use, terminal autonomy, and native voice. Different ceilings for different jobs.
| Claude Fable 5 | GPT-5.5 | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Released | 2026-06-09 | 2026-04-23 |
| Context | 1M | 1M |
| Max output | 128K | 128K |
| Input /1M | $10.00 | $5.00 |
| Output /1M | $50.00 | $30.00 |
| Modalities | text, vision, code | text, vision, audio, video |
The analysis
The launch-window headline is the SWE-Bench Pro gap: Fable 5 at ~80% versus GPT-5.5’s 58.6% — a 21-point lead on a contamination-resistant agentic-coding benchmark (vendor-claimed until independently reproduced). Fable 5 also posts 95.0% SWE-Bench Verified and leads both FrontierCode subsets. GPT-5.5’s strengths sit on a different axis: 84.9% GDPval, 78.7% OSWorld computer use, 98% Tau2 Telecom, and native voice.
Pricing favors GPT-5.5 on paper — $5/$30 against Fable 5’s $10/$50 — but GPT-5.5’s figure already reflects its April doubling, and output-heavy agentic work narrows the real-world gap via token efficiency. For pure coding-agent workloads the benchmark delta dominates the price delta; for computer-use automation the reverse.
Honest caveat: we have four first-party eval rounds for Fable 5 vs Opus 4.8 (receipts published), but no first-party Fable-vs-GPT rounds yet — this comparison rests on launch-window vendor figures from both labs. We mark claims accordingly and will receipt a cross-lab round.
Pick Claude Fable 5 if…
- Agentic coding is the core workload (SWE-Bench Pro / Verified lead)
- You operate inside Claude Code or the Anthropic agent stack
- Long-horizon tasks where the lead reportedly widens
Pick GPT-5.5 if…
- Computer-use / OSWorld-style autonomous desktop automation
- Customer-workflow agents (Tau2 Telecom 98%) and native voice
- Output-heavy workloads where $5/$30 plus token efficiency wins
Claude Fable 5
Mythos-class made generally available — the new agentic-coding ceiling, at 2× Opus pricing.
GPT-5.5
OpenAI’s agentic flagship: best-in-class computer-use and knowledge-work scores, at double the price.