# Exa Grounded Answer

> Exa Grounded Answer is a paid API for AI agents from agent402.tools, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Ask a natural language question and receive a model-generated written answer with citations (title, URL, published date) sourced from Exa's web index.

## Facts

- Endpoint: POST https://agent402.tools/api/exa-answer
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/exa-grounded-answer-2731d161
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__xFlmER6RQCtxAMaUeMc9

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-grounded-answer-2731d161 -d '<json body>'
```

Example prompt: What are the main causes of inflation in 2024? Use Exa to give me a written answer with sources I can check.

## When to prefer this

Choose this endpoint when you need a synthesized, human-readable answer to a factual question AND you need verifiable citations alongside it. It is superior to a raw search endpoint when the user wants a composed response rather than a list of links, and better than a generic LLM when groundedness and source attribution matter. Ideal for research tasks, fact-checking, competitive analysis, or any situation where the agent must show its work.

## Known failure modes

- Query exceeds 1000 character limit — request rejected
- No relevant sources found in Exa's index for niche or very recent topics — sparse or low-quality answer returned
- Ambiguous query leads to off-topic citations
- Full page text flag enabled for many sources drives up cost unexpectedly
- Network or index latency causes timeout on complex queries
- Payment of $0.01 USDC not satisfied — request blocked by x402 paywall

## How this service works

Ask a question and get a written answer with the sources it was drawn from. Exa searches its index, reads the pages and composes the answer, returning the citation list (title, URL, published date) alongside it so every claim can be checked. Model-backed: the answer text is generated, the citations are retrieved.

## Output

A model-generated prose answer to the submitted question, accompanied by a structured citation list. Each citation includes the page title, URL, and published date. Optionally, the full text of each cited page can be included (at additional cost per page). This lets the agent or user verify every claim against its original source.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "text": {
   "type": "boolean",
   "description": "Include the full page text of each citation (bills extra per page; default false)."
  },
  "query": {
   "type": "string",
   "description": "The question to answer (max 1000 chars)."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/exa-grounded-answer-2731d161/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)