# Exa Neural Web Search

> Exa Neural Web Search is a paid API for AI agents from agent402.tools, paid per call via x402, $0.012/call, status unknown (last checked 2026-09-14).

Performs meaning-based (embedding) web search over Exa's curated index, returning up to 10 results ranked by semantic relevance rather than keyword overlap.

## Facts

- Endpoint: POST https://agent402.tools/api/exa-search
- Price: $0.012/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/exa-neural-web-search-e9e0badd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Mdcump5x3KZ1I__I4pWSC

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability exa-neural-web-search-e9e0badd -d '<json body>'
```

Example prompt: Search the web for pages explaining how transformer attention mechanisms relate to memory retrieval in cognitive science — use neural search and limit it to academic or research content from 2022 onward, returning 5 results.

## When to prefer this

Prefer this endpoint when a keyword search returns irrelevant results due to vocabulary mismatch, when the user's intent is conceptual or abstract rather than a specific phrase, when searching for niche technical writing or research papers on emerging topics, or when you need 'pages like this idea' style retrieval. Use over a keyword-based engine (e.g. Brave) when the query is a question, a description, or a concept rather than a set of terms.

## Known failure modes

- Query exceeds 1000 characters — request rejected
- numResults out of range (must be 1–10) — validation error
- Invalid ISO date format for startPublishedDate or endPublishedDate — parsing error
- Category filter value not recognized by Exa — may return empty or degraded results
- Conflicting includeDomains and excludeDomains — unpredictable filtering behavior
- Exa index does not cover very recent or paywalled content — may return outdated results
- Payment failure (x402 protocol) — call not executed, 402 response returned

## How this service works

Neural (embedding-based) web search over Exa's curated index, which finds pages by meaning rather than keyword overlap. Use it when a keyword engine returns the wrong thing: conceptual questions, 'pages like this one', or niche technical writing. Returns up to 10 results with title, URL, published date and author. Complements the Brave-backed web search rather than replacing it.

## Output

Returns up to 10 web page results, each containing the page title, URL, published date, and author. Results are ranked by semantic similarity to the query rather than keyword frequency, surfacing conceptually relevant pages that keyword engines typically miss.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "type": {
   "type": "string",
   "description": "auto (default), neural, or keyword."
  },
  "query": {
   "type": "string",
   "description": "What to search for, in natural language (max 1000 chars)."
  },
  "category": {
   "type": "string",
   "description": "Optional Exa category filter, e.g. 'research paper', 'news', 'company'."
  },
  "numResults": {
   "type": "number",
   "description": "Results to return, 1 to 10 (default 10)."
  },
  "excludeDomains": {
   "type": "array",
   "description": "Never return results from these domains."
  },
  "includeDomains": {
   "type": "array",
   "description": "Only return results from these domains."
  },
  "endPublishedDate": {
   "type": "string",
   "description": "ISO date; only pages published on or before it."
  },
  "startPublishedDate": {
   "type": "string",
   "description": "ISO date; only pages published on or after it."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/exa-neural-web-search-e9e0badd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)