GPT-5.6 Sol vs Claude Fable 5 vs Kimi K3 (2026)
GPT-5.6 Sol vs Claude Fable 5 vs Kimi K3 (2026)
The three most capable models of July 2026 each win a different crown: GPT-5.6 Sol (agentic reasoning), Claude Fable 5 (hardest coding), and Kimi K3 (top capability at half the price). Here’s the breakdown.
Last verified: July 25, 2026
Head to Head
| GPT-5.6 Sol | Claude Fable 5 | Kimi K3 | |
|---|---|---|---|
| Vendor | OpenAI | Anthropic | Moonshot AI |
| License | Proprietary | Proprietary | Open weights (Jul 27) |
| Input / Output (per MTok) | $5 / $30 | $10 / $50 | $3 / $15 (flat) |
| Cost / task (30K→5K) | ~$0.30 | ~$0.55 | ~$0.165 |
| Agents’ Last Exam | 53.6 (new high) | 40.5 (−13.1) | — |
| SWE-bench Pro | ~64.6 (est.) | ~80.3 | — |
| Intelligence Index | Top tier | Top tier | ~57 (#3 overall) |
| Best for | Agentic reasoning | Real-codebase coding | Top capability, low cost |
GPT-5.6 Sol — agentic reasoning king
Sol set a new high of 53.6 on Agents’ Last Exam (long-running professional workflows across 55 fields), eclipsing Claude Fable 5’s adaptive-reasoning score by 13.1 points, and averages roughly 92 on agentic tasks in head-to-head comparisons. At $5/$30, it’s the pick for the hardest long-horizon agent work. Pick Sol when the job is long, multi-step, and reasoning-heavy.
Claude Fable 5 — hardest-coding specialist
Fable 5 is Anthropic’s frontier coding/reasoning model. On SWE-bench Pro (patch generation for real GitHub issues) it scores about 80.3%, beating Sol’s estimated ~64.6% by more than 15 points. At $10/$50 it’s the most expensive here, and since July 20, 2026 it’s gated to Max / Team-Premium subscription tiers (50% weekly cap). Pick Fable 5 when fixing and patching real, existing codebases is the core job.
Kimi K3 — top capability, half the price
Moonshot’s Kimi K3 (2.8T MoE, 1M context, native vision) scores about 57 on the Artificial Analysis Intelligence Index, ranking #3 overall behind only Fable 5 and Sol — the first open-weight model to reach that tier. With open weights on July 27, 2026 and flat $3/$15 pricing (~$0.165/task), it delivers frontier-tier intelligence at roughly half the cost of the US flagships. It trails them on specific agentic/coding sub-benchmarks, but the capability-per-dollar is unmatched at the top. Pick K3 when you want near-frontier quality cheaply, or need open weights for on-prem/compliance.
The Winning Pattern
- Default to Kimi K3 for top-tier work where cost matters.
- Escalate to GPT-5.6 Sol for the hardest long-horizon agents.
- Escalate to Claude Fable 5 for real-codebase patch generation.
Bottom Line
- Cheapest of the top tier: Kimi K3 (~$0.165, open weights Jul 27)
- Best agentic reasoning: GPT-5.6 Sol (~$0.30)
- Best real-codebase coding: Claude Fable 5 (~$0.55)
The story of July 2026: an open-weight model finally sits shoulder-to-shoulder with the US frontier — at half the price.