Gemini 3.8 Flash is the best AI for knowledge-base search in most setups. Search and retrieval-augmented answering run on every query, so speed and cost per call matter, and Gemini 3.8 Flash is fast, cheap at $0.75/$3.75, and holds a million tokens of retrieved context. When answers must be synthesised carefully from long policy or technical documents, Claude Sonnet 5.5 is the more careful reader; for very simple lookups at huge volume, GPT-6 Luna costs $0.10 per million input tokens.
The safest knowledge base search default, the cheaper option worth trying first, and the specialist pick — before you read the detail below.
Gemini 3.8 Flash is the strongest answer here for knowledge base search — pick it when quality of output matters more than the $0.75/1M/1M input you pay for it.
GPT-6 Luna handles the same job for about 87% less per token. Start here and only move up if the output is not good enough.
Claude Sonnet 5.5 is the fastest of these for knowledge base search — worth it when latency is what the reader notices, not the last few points of reasoning depth.
Gemini 3.8 Flash is the best default for retrieval answers — fast, cheap, 1M-token window.
Claude Sonnet 5.5 is the step up when answers depend on careful reading of dense documents.
GPT-6 Luna is the cheapest capable option for simple lookups at very high volume.
Use Gemini 3.8 Flash for internal search, help-desk lookups and everyday questions over your docs.
Use Claude Sonnet 5.5 for dense policies, contracts and technical documentation.
Use Gemini 3.1 Pro when your knowledge base already lives in Google Drive and Workspace.
Switch the scoring lens to see whether the knowledge base search answer changes when cost, speed, or long-document depth leads the decision.
Anthropic / Balanced / Oct 10, 2026
Near-Opus 5.5 quality on scoped work at half the price.
Ranks models by the broadest mix of coding, writing, research, and long-context usefulness.
The work is long, ambiguous and multi-step — Anthropic positions Opus 5.5 for exactly that — or you need the lowest possible price, where Haiku 5.5 costs a twentieth as much.
Where the knowledge base search recommendation shifts once you weigh price or latency differently.
Google's fast agentic workhorse — strong coding at Flash pricing.
Near-Opus 5.5 quality on scoped work at half the price.
OpenAI's budget tier at half the old price.
Best for research and deep document analysis — 2M context at the best premium price.
List prices and published scores — the numbers this page's pick is built from.
| Model | Input | Output | Est. month | Context | Speed | Coding | Writing | Research |
|---|---|---|---|---|---|---|---|---|
| Gemini 3.8 FlashGoogle | $0.75/1M | $3.75/1M | $15 | 1M tokens | Very fast | 92 | 86 | 89 |
| Claude Sonnet 5.5Anthropic | $2.00/1M | $10.00/1M | $40 | 1M tokens | Fast | 98 | 98 | 95 |
| GPT-6 LunaOpenAI | $0.10/1M | $0.50/1M | $2.00 | 1.1M tokens | Very fast | 84 | 82 | 80 |
| Gemini 3.1 ProGoogle | $2.00/1M | $12.00/1M | $44 | 2M tokens | Balanced | 80 | 82 | 99 |
Scores out of 100 — how we evaluate models. “Est. month” is 10M in / 2M out at list price: a ceiling, no discounts.
Why each one is on the shortlist for knowledge base search, what it is genuinely good at, and where we would steer you away from it.
Our pick for knowledge base search. It scores 92/100 on the coding axis we weight this page by, and nothing else in this shortlist matches it on output quality.
Google's September 2, 2026 Flash model, positioned as the agentic workhorse of the Gemini 3 family — stronger coding and terminal work than 3.7 Flash at the same $0.75/$3.75 price.
You need long single responses (65K output cap) or your workload is output-heavy enough that its verbosity erases the per-token saving.
The fastest capable model in its price range. Gemini 3.8 Flash is the pick for multimodal and terminal-heavy agent work on a budget; just measure cost per task, not per token, because it writes a lot.
Full pricing, benchmark table and release notes on the Gemini 3.8 Flash page.
Here for latency: it answers fastest of anything listed for knowledge base search, at 98/100 on coding.
Anthropic's September 28, 2026 Sonnet — built for well-scoped everyday work like features, bug fixes, documents, slides and spreadsheets, priced at $2/$10 and close to Opus 5.5 on most of Anthropic's launch rows.
The work is long, ambiguous and multi-step — Anthropic positions Opus 5.5 for exactly that — or you need the lowest possible price, where Haiku 5.5 costs a twentieth as much.
The model most people should default to in the Claude lineup. Sonnet 5.5 lands within a few points of Opus 5.5 on most of Anthropic's launch rows, beats it on Terminal-Bench 4.0, and costs half as much. Step up to Opus 5.5 only when the task is open-ended and long.
Full pricing, benchmark table and release notes on the Claude Sonnet 5.5 page.
The cost-conscious pick for knowledge base search, about 87% less per token than Gemini 3.8 Flash than the top choice while holding 84/100 on coding.
OpenAI's budget tier at half the old price. Full GPT-6 Luna review →
The alternative to check next for knowledge base search — 80/100 on coding.
Best for research and deep document analysis — 2M context at the best premium price. Full Gemini 3.1 Pro review →
UseRightAI recommendations are based on practical decision factors people actually feel in day-to-day use.
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For knowledge base search, Gemini 3.8 Flash (Google) is our pick. Google's fast agentic workhorse — strong coding at Flash pricing. It costs $0.75/1M input and $3.75/1M output tokens, with a 1M-token context window — enough headroom for all but the largest knowledge base search jobs. Claude Sonnet 5.5 is the closest alternative if it doesn't fit your setup.
Because the work it is built for overlaps closely with knowledge base search: terminal and coding agents — Google reports 90.8% on Terminal-Bench 2.1, up from 81.6% for 3.7 Flash and video, image and PDF understanding in one 1M-context call. The fastest capable model in its price range. Gemini 3.8 Flash is the pick for multimodal and terminal-heavy agent work on a budget; just measure cost per task, not per token, because it writes a lot.
On a moderate month — 10M input and 2M output tokens — Gemini 3.8 Flash runs about $15.00 at list price, with no batch or caching discounts applied, so treat that as a ceiling. GPT-6 Luna is the cheaper route at roughly $2.00 for the same volume, if knowledge base search is high-volume enough for price to lead the decision.
Verbose: Artificial Analysis needed 120M output tokens to run its index against a 71M median, so cost per task runs above the sticker price. 65K max output — half of what Claude and OpenAI's current models allow. Avoid it if you need long single responses (65K output cap) or your workload is output-heavy enough that its verbosity erases the per-token saving. None of that rules it out for knowledge base search on its own — but if one of those limits maps onto how you actually work, take the alternative on this page seriously rather than defaulting to the top pick.
GPT-6 Luna at $0.1/1M input is the budget option here. OpenAI's budget tier at half the old price. Expect a quality step down on the hardest cases — the usual pattern is to route routine knowledge base search volume to GPT-6 Luna and keep Gemini 3.8 Flash for the work where a wrong answer is expensive.