Claude Fable 5 vs Kimi K3 vs GPT-5.6 Sol: The Real 2026 Frontier Showdown

TL;DR: Per Artificial Analysis, Claude Fable 5 still leads the Intelligence Index at 60, GPT-5.6 Sol sits one point behind at 59 with the #1 Coding Agent Index score (80), and Moonshot AI's Kimi K3 lands at 57 — within three points of the leader at roughly 1/3.3 of Fable's blended API cost ($12.00 vs $40.00 per million tokens on a standard chat mix). On TulexAI that gap reads 7 PT vs 25 PT per message. Fable is the pick for the hardest long-horizon agent work (Pro plan and up), Sol for coding agents, K3 for frontier-class reasoning on a budget. All three are live on TulexAI today.

Who these three actually are

Claude Fable 5 is Anthropic's frontier model and the current Intelligence Index leader. It ships with adaptive thinking always on — it reasons before every answer, which makes it slower but is a big part of why it tops the board. 1M-token context, 128K max output, $10/$50 per million tokens. On TulexAI it costs 25 PT per message and is available on the Pro plan ($23/mo) and up.

GPT-5.6 Sol is OpenAI's flagship of the GPT-5.6 family we covered when it launched. Its calling card isn't the Intelligence Index (a very close 59) — it's coding agents, where it ranks #1 outright, and token efficiency: about 15K output tokens per Index task, which quietly compounds into real savings. $5/$30 per million tokens, 12 PT per message, every TulexAI plan.

Kimi K3 is the newcomer. Moonshot AI shipped it on July 16, 2026, and it immediately posted an Intelligence Index of 57 — #7 of 190 models tracked by Artificial Analysis — at $3/$15 per million tokens with a 1M-token context window and a 90%-off cached-input rate ($0.30). It's a deep-reasoning model: brilliant, and in no hurry (more on that below). It's been live on TulexAI since launch day at 7 PT per message, on every plan from $11/mo. And as of today, two siblings join it: Kimi K2.6 ($0.95/$4, 262K context, text + image + video input, thinking and non-thinking modes) at 2 PT, and Kimi K2.7 Code ($1.90/$8, an agentic coding model) at 4 PT — both on every plan.

What the benchmarks actually say

Every number here comes from Artificial Analysis, the closest thing to a neutral scoreboard:

• Intelligence Index: Fable 5 scores 60 (the leader), Sol 59, Kimi K3 57 (#7 of 190 models). Three points cover all three — this is a photo finish at the top of a 190-model field.
• Coding agents: Sol takes the #1 spot on the Coding Agent Index with 80, ahead of its own siblings Terra (77) and Luna (75). Neither Fable nor K3 tops that board — if your work lives in a coding agent, Sol is the measured leader.
• Long-horizon agents: on AA-Briefcase, the rubric-scored agentic eval, Fable 5 posts 56% — the score that keeps it the pick for sprawling multi-step tasks where a model has to stay coherent over hours of tool calls.
• Speed: the one board where K3 falls hard. Artificial Analysis measured 32.6 tokens/sec output — #147 of 190 — and roughly 161 seconds to first token on their test. It thinks deeply before it speaks. Literally.

Read that honestly: Fable is still the smartest model money can buy, Sol is the best coding agent money can buy, and K3 is 95% of the leader's Index score at a fraction of the price — as long as you're not in a hurry.

Pricing: where the three-point gap becomes a 3.3× gap

List prices per million tokens: Fable 5 $10 in / $50 out, Sol $5 / $30, K3 $3 / $15 (with cached input at $0.30 — 90% off, verified against platform.kimi.ai). On the standard 0.25/0.75 chat blend, that works out to $40.00 vs $23.75 vs $12.00 per million tokens. K3 delivers a 57 Intelligence Index at 1/3.3 the blended cost of the 60-scoring leader.

On TulexAI the same ratio shows up in Platform Tokens: Fable 5 is 25 PT, Sol is 12 PT, K3 is 7 PT per message. The Kimi models and Sol are on every plan from $11/mo; Fable 5 requires Pro ($23/mo) or above. Full plan details are on the pricing page.

Side by side: the specs that matter

	Claude Fable 5	GPT-5.6 Sol	Kimi K3
AA Intelligence Index	60 (leader)	59	57 (#7 of 190)
AA Coding Agent Index	—	80 (#1)	—
AA-Briefcase (long-horizon agents)	56%	42%	—
Output speed (AA)	Slower (adaptive thinking always on)	Token-efficient (~15K out/task)	32.6 tok/s (#147 of 190)
Context window	1M	—	1M
API price (in/out per 1M)	$10 / $50	$5 / $30	$3 / $15 (cached $0.30)
Blended $/MTok (0.25/0.75)	$40.00	$23.75	$12.00
On TulexAI	25 PT — Pro ($23) and up	12 PT — every plan	7 PT — every plan

Which one for which job

• Pick Claude Fable 5 when the task is genuinely hard and long: multi-hour agent runs, careful synthesis across a 1M-token corpus, work where a wrong step at hour three costs you the whole run. Its 56% AA-Briefcase score is the widest lead any of the three holds on any board. Budget 25 PT per message and a Pro plan or above.
• Pick GPT-5.6 Sol when you're building or driving coding agents. #1 on the Coding Agent Index, and its ~15K-output-tokens-per-task efficiency means the per-task bill undercuts what the list price suggests. 12 PT, any plan.
• Pick Kimi K3 when you want frontier-class reasoning at the lowest cost — research, analysis, hard reasoning over huge documents (1M context), high-volume work where 25 PT per message would sting. At 7 PT it's the cheapest seat within three Index points of the leader. For quick everyday chat, its new sibling K2.6 at 2 PT is the better default; for agentic coding on a budget, K2.7 Code at 4 PT.

The honest caveats

We sell honest billing, so here's the fine print each vendor won't headline. K3 is slow to start: ~161 seconds to first token on Artificial Analysis' test and #147 of 190 on output speed. It's a deep-reasoning model — superb for "go away and think," frustrating for rapid back-and-forth. Fable is the priciest seat in the house — $40.00 blended per million tokens, 25 PT per message, and Pro-and-up only on TulexAI — and its always-on adaptive thinking means it's never the fast option either. Sol wins coding but not everything: it trails Fable by 14 points on AA-Briefcase, so "the coding king" and "the agent king" are currently different models.

Which is the real conclusion: in July 2026 there is no single best model — there's a best model per job, and it changed twice this month. That's the argument for an aggregator over any single $20–30/mo vendor subscription: on TulexAI all three sit on one login next to 50 models in all, with a live token meter showing the PT cost before you send. If you're weighing this against a ChatGPT subscription, the full comparison is here.

Try all three free on TulexAI — no card, first prompts on us. Run the same prompt through Fable, Sol and K3 and let the answers settle it.

Frequently Asked Questions

Is Kimi K3 as good as Claude Fable 5?

Close, but not equal. On the Artificial Analysis Intelligence Index, Fable 5 scores 60 and K3 scores 57 (#7 of 190 models) — a real but small gap. Fable also leads long-horizon agent work (56% on AA-Briefcase). K3's case is cost: about 1/3.3 of Fable's blended API price, and 7 PT vs 25 PT per message on TulexAI.

How much does Kimi K3 cost?

Via the Moonshot AI API: $3 per million input tokens, $15 per million output, with cached input at $0.30 — 90% off (verified against platform.kimi.ai, July 2026). On TulexAI it's 7 PT per message on every plan from $11/mo, no separate Moonshot account needed.

Why is Kimi K3 so slow?

By design. It's a deep-reasoning model that thinks extensively before answering — Artificial Analysis measured roughly 161 seconds to first token and 32.6 tokens/sec output (#147 of 190). Use it for hard problems where quality beats latency; for snappy everyday chat, Kimi K2.6 (2 PT) or GPT-5.6 Sol (12 PT) are better fits.

Which model is best for coding?

By the numbers, GPT-5.6 Sol: #1 on the Artificial Analysis Coding Agent Index with a score of 80, ahead of Terra (77) and Luna (75). It's 12 PT per message on every TulexAI plan. If you want a budget coding agent, the new Kimi K2.7 Code runs 4 PT per message.

Do I need the Pro plan to use these models?

Only for Fable 5, which is available on Pro ($23/mo), VIP ($46) and Elite ($99). GPT-5.6 Sol, Kimi K3, Kimi K2.6 and Kimi K2.7 Code are all included on every plan, starting with Basic at $11/mo — alongside 50 models in all. Start free and your first prompts are on us.