# Deep Research vs Web Search

Both tools fetch information from the open web. They serve very different goals.

## Side-by-side

|  | Web Search | Deep Research (fast) | Deep Research (deep) |
|  --- | --- | --- | --- |
| **Latency** | sub-15s | ~10 – 15s | 2 – 10 min |
| **Rounds** | 1 | 1 | 1 – 10 |
| **Sources per query** | 5 – 10 | 10 – 20 | 30 – 60+ |
| **Link-following** | no | no | yes |
| **Reflection** | no | no | yes |
| **Final report** | inline summary | inline cited summary | structured markdown report |
| **Streaming progress** | no | no | yes (Server-Sent Events) |
| **Cost** | low | low – medium | medium – high |
| **Best for** | quick fact lookup, current events | quick cited summary | thorough investigation, comparisons |


## Pick Web Search when

- The user asks for a single fact or a quick answer ("what is X?", "who is Y?").
- Live data is required (stock price, weather, sports score).
- Sub-15s response is non-negotiable.
- A single source is sufficient.


## Pick Deep Research (fast) when

- The user wants a short cited summary across a handful of sources.
- The model needs to ground a claim in evidence before continuing the conversation.
- Latency must stay in the same range as Web Search but with citations.


## Pick Deep Research (deep) when

- The user asks for a comparison across many sources ("compare 5 boutique hotels…").
- The user wants a literature review, market scan, or research brief.
- The investigation needs to follow citations across pages and reflect on gaps.
- A streaming progress UI is acceptable.


## Configuring Tool Selection

When both tools are enabled on an assistant, the model decides which to use based on the user's query. You can bias the model with the assistant's `instructions`:


```text
You have access to web_search for quick lookups and deep_research for
multi-source investigations. Default to web_search for single questions;
use deep_research only when the user explicitly asks for a thorough
analysis, a comparison, or a research report.
```

You can also disable mode selection on Deep Research so the model can only invoke a single mode.

## Related Resources

- [Web Search](/docs/documentation/system-tools/web-search) — Quick fact lookup tool.
- [Deep Research](/docs/documentation/system-tools/deep-research) — Multi-round research tool.
- [Assistants](/docs/documentation/core-concepts/assistants) — Configuring an assistant's toolset.
- [Stream Research Events](/assets/stream-events.2463096b5ec9957aa90b2b706f6309530b612196a2afe7bfcdc9b910609ebd71.79a4f7ef.md) — Live progress for deep sessions.