Best AI model for agents: how to choose

There is no single best AI model for agents; it depends on budget, input size and whether you need to self-host. Highest of these on the official Terminal-Bench 4.0 board: Claude Opus 5.5. Lowest listed price: Mercury 3. Largest context window: GPT-6.1 Terra. Open weights: MiniMax M3.1 Flash. Every pick follows one stated fact, linked to its source. We have not run these models.

Reported Updated Oct 29, 2026 · Markdown · All models

Pick by what limits you

Highest of these on the official Terminal-Bench 4.0 board

Claude Opus 5.5

64.8% on the official Terminal-Bench 4.0 board (snapshot Oct 26, 2026), the highest of the agent models in our data that appear on it. Independent board, not our test. Source

Lowest listed price

Mercury 3

$0.1 in / $0.35 out per 1M tokens (temporary price), the lowest of the generally available agent models listed here. Source

Largest context window

GPT-6.1 Terra

1,050,000 tokens, the largest published among the generally available agent models here (tied; newest shown). Source

Open weights

MiniMax M3.1 Flash

Newest generally available agent model here with downloadable weights (MiniMax Community License); $0.15 in / $0.6 out per 1M tokens on the vendor API. Source

Each pick follows one stated rule over our sourced data, so it moves when the data does. This is a way to choose, not a quality ranking: we have not run these models.

All models in scope (29)

Language models in our data released in the 120 days before Oct 29, 2026 that their vendors position for long-running, tool-using work. Our data is not every model on the market.

Best AI model for agents: how to choose: models in scope with sourced facts
Model	Price (listed)	Context	Licence	Input	Released	Status
Gemini 4 CarbonGoogle	$2 in / $10 out per 1M tokens (introductory price, end date not stated; list $4 / $20)source	Not published	Proprietarysource	Not published	Oct 28, 2026source	Limited access
GPT-6.1 TerraOpenAI	$1 in / $5 out per 1M tokenssource	1.05M tokenssource	Proprietary (API)source	text, imagesource	Oct 26, 2026source	Generally available
Kimi K3.1 ProMoonshot AI	$2 in / $10 out per 1M tokenssource	1.05M tokenssource	Not yet publishedsource	Not published	Oct 23, 2026source	Generally available
Kimi K3.1 Pro HighspeedMoonshot AI	$4 in / $20 out per 1M tokenssource	1.05M tokenssource	Not published	Not published	Oct 23, 2026source	Generally available
Mercury 3Inception	$0.1 in / $0.35 out per 1M tokens (launch promo, end date not stated; list $0.2 / $0.7)source	1M tokenssource	Proprietary (API)source	Not published	Oct 19, 2026source	Generally available
MiniMax M3.1 FlashMiniMax	$0.15 in / $0.6 out per 1M tokenssource	1M tokenssource	MiniMax Community Licensesource	text, image, videosource	Oct 19, 2026source	Generally available
Gemini 4 ArgonGoogle	$2 in / $10 out per 1M tokens (introductory price until Nov 30, 2026; list $4 / $20)source	1.05M tokenssource	Proprietary (API)source	text, image, video, audio, pdfsource	Oct 13, 2026source	Generally available
Muse WonderMeta	$4 in / $20 out per 1M tokenssource	1.05M tokenssource	Proprietary (API)source	text, image, video, audio, pdfsource	Oct 12, 2026source	Public preview
Muse Wonder FullMeta	Not published	Not published	Proprietary (subscription)source	Not published	Oct 12, 2026source	Limited access
Claude Haiku 5.5Anthropic	$0.1 in / $0.5 out per 1M tokenssource	1M tokenssource	Proprietary (API)source	text, imagesource	Oct 7, 2026source	Generally available
GPT-6.1 SolOpenAI	$2 in / $10 out per 1M tokenssource	1.05M tokenssource	Proprietary (API)source	text, imagesource	Sep 29, 2026source	Generally available
Claude Sonnet 5.5Anthropic	$2 in / $10 out per 1M tokenssource	1M tokenssource	Proprietary (API)source	text, imagesource	Sep 28, 2026source	Generally available
Claude Opus 5.5Anthropic	$4 in / $20 out per 1M tokenssource	1M tokenssource	Proprietary (API)source	text, imagesource	Sep 22, 2026source	Generally available
GPT-6 SolOpenAI	$2 in / $10 out per 1M tokenssource	Not published	Proprietary (API)source	text, imagesource	Sep 22, 2026source	Generally available
Grok 4.7xAI	$2 in / $6 out per 1M tokenssource	500K tokenssource	Proprietary (API)source	text, imagesource	Sep 21, 2026source	Generally available
Claude Fable 5.1Anthropic	$10 in / $50 out per 1M tokenssource	1M tokenssource	Proprietary (API)source	text, imagesource	Sep 15, 2026source	Generally available
GPT-6 AstraOpenAI	$10 in / $50 out per 1M tokenssource	1.05M tokenssource	Proprietary (API)source	text, imagesource	Sep 3, 2026source	Generally available
Gemini 3.8 FlashGoogle	$0.75 in / $3.75 out per 1M tokens (temporary price until Dec 31, 2026; list $1.5 / $7.5)source	1.05M tokenssource	Proprietary (API)source	text, image, video, audio, pdfsource	Sep 2, 2026source	Generally available
Claude Mythos 5.1Anthropic	$10 in / $50 out per 1M tokenssource	1M tokenssource	Proprietary (API)source	Not published	Sep 1, 2026source	Limited access
GLM-5.3-FlashZ.ai	Not published	Not published	Not published	Not published	Aug 26, 2026source	Generally available
GLM-5.3Z.ai	$1.4 in / $4.4 out per 1M tokenssource	1.05M tokenssource	GLM-5.3 License (MIT-style plus a MaaS condition)source	Not published	Aug 14, 2026source	Generally available
Grok 4.6xAI	$2 in / $6 out per 1M tokenssource	500K tokenssource	Proprietary (API)source	text, imagesource	Aug 12, 2026source	Generally available
Gemini Robotics ER 2Google	Not published	Not published	Proprietary (API)source	Not published	Jul 30, 2026source	Public preview
Claude Opus 5Anthropic	$5 in / $25 out per 1M tokenssource	1M tokenssource	Proprietary (API)source	Not published	Jul 24, 2026source	Generally available
Gemini 3.5 Flash-LiteGoogle	Not published	1.05M tokenssource	Proprietary (API)source	text, image, video, audio, pdfsource	Jul 21, 2026source	Generally available
Gemini 3.6 FlashGoogle	Not published	1.05M tokenssource	Proprietary (API)source	text, image, video, audio, pdfsource	Jul 21, 2026source	Generally available
Kimi K3Moonshot AI	$3 in / $15 out per 1M tokenssource	1M tokenssource	Kimi K3 License (custom)source	Not published	Jul 16, 2026source	Generally available
GPT-5.6 SolOpenAI	$4 in / $20 out per 1M tokens (promotional price, OpenAI says it is available at least through Nov 21, 2026; list price after the promo not stated)source	1.05M tokenssource	Proprietary (API)source	text, imagesource	Jul 9, 2026source	Generally available
Grok 4.5xAI	$2 in / $6 out per 1M tokenssource	500K tokenssource	Proprietary (API)source	text, imagesource	Jul 8, 2026source	Generally available

FAQ

What is the best AI model for agents right now?

It depends on what limits you. Highest of these on the official Terminal-Bench 4.0 board: Claude Opus 5.5. Lowest listed price: Mercury 3. Largest context window: GPT-6.1 Terra. Open weights: MiniMax M3.1 Flash. Each pick names the fact behind it and links to the source.

Which agent model is cheapest?

Mercury 3: $0.1 in / $0.35 out per 1M tokens (temporary price). Next: Claude Haiku 5.5 ($0.1 in / $0.5 out per 1M tokens); MiniMax M3.1 Flash ($0.15 in / $0.6 out per 1M tokens).

Is there an open-weight model for agents?

Yes: MiniMax M3.1 Flash (MiniMax Community License), GLM-5.3 (GLM-5.3 License (MIT-style plus a MaaS condition)), Kimi K3 (Kimi K3 License (custom)).

Did you test these models as agents?

No. This page is Reported. Prices, context windows and licences come from the vendor pages linked in the table; the Terminal-Bench 4.0 score comes from the official board, not from us.

OpenAI GPT-6.1 Terra: a $1/$5 computer-use model, and what the launch post leaves out (Reported; first seen 2026-10-26 19:05 UTC)

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