# Evidence for Agents

> Independent public-source evidence. Claim/question → Evidence Pack. Machine-first, pay per request.

## Discover
- OpenAPI: https://evidenceforagents.com/openapi.json
- Documentation: https://evidenceforagents.com/docs
- Prices and availability: https://evidenceforagents.com/api/v1/pricing
- Health: https://evidenceforagents.com/api/v1/health?ready=1
- Example pack (FICTIONAL, not live evidence): https://evidenceforagents.com/examples/evidence-pack.json

## Pricing
Quick: $0.10; standard: $0.50; deep: $1.50.
Prices are per completed research request, including insufficient evidence. Check the price endpoint for current network and availability. No subscriptions or customer API keys.

## Use
1. POST https://evidenceforagents.com/api/v1/verify with Content-Type: application/json and a random UUID Idempotency-Key. Keep this key secret and stable for all retries.
2. JSON: {"claim":"Your claim or question", "url":"https://example.com", "tier":"standard"}. URL optional. Alternatively supply question or subject. At least one input required; do not send both claim and question.
3. Decode the HTTP 402 PAYMENT-REQUIRED header. Approve only the quoted exact USDC amount, asset, network, recipient and resource. Use an x402 v2 EVM client to sign a 300-second EIP-3009 authorization. Mainnet is Base eip155:8453; testnet is Base Sepolia eip155:84532. Never send a private key to the service.
4. Retry the exact same JSON and Idempotency-Key, adding PAYMENT-SIGNATURE. Use a client timeout of at least 180 seconds. Research runs before settlement.
5. HTTP 200 returns the Evidence Pack at top level, access.access_token and PAYMENT-RESPONSE. Keep the result token secret.
6. HTTP 202: poll GET /api/v1/requests/{id} with Authorization: Bearer <access_token>, every 5 seconds. Do not pay again.
7. If the connection breaks or HTTP 500 occurs, retry the identical POST with the same Idempotency-Key before generating a new payment. A stored request is recovered without another settlement.
8. A terminal failed request requires a new Idempotency-Key and authorization. Provider failure before settlement is not charged. An uncertain settlement stays pending until reconciled on-chain.

## Interpret
Statuses: supported, contradicted, mixed, insufficient_evidence.
Source evidence → quoted facts → reasoned conclusion. Facts and conclusions are machine interpretations. Every fact references a source and verbatim excerpt. Conflicting evidence is retained. Confidence is a heuristic evidence-strength score, not a probability. retrieved_at is observation time, not publication time. Sources may be cached by providers. Never discard limitations, contradictions or research.demo. A demonstration pack is not evidence.

## Privacy and limits
12 KiB JSON maximum. No secret/confidential input. Input goes to Tavily and Anthropic in live/testnet modes. Results require a bearer capability token. No public result index. No arbitrary server-side URL fetches; public HTTP(S) URLs only. Polling is recovery, not an asynchronous job queue.