VerifyAPI MCP Server
Fact-check any claim before you act on it. One tool. Live web sources. Cryptographically signed receipts.
What it does: VerifyAPI is a Model Context Protocol server that verifies factual claims against live web sources and returns a citable verdict — including the source URL, published date, a verbatim quote, and an Ed25519-signed receipt so downstream systems can prove the check actually happened.
When to use it: Any time your agent is about to act on a factual claim it can't cite. Prices, dates, versions, quotes, statistics, product specs, event outcomes. If getting it wrong would cost time, money, or trust — verify first.
Quick install (Claude Desktop / Cursor / Cline / any MCP client)
{
"mcpServers": {
"verifyapi": {
"command": "npx",
"args": ["-y", "@verify-api/mcp@latest"],
"env": {
"VERIFYAPI_API_KEY": "csk_live_..."
}
}
}
}
No API key? Leave VERIFYAPI_API_KEY unset for the free trial (limited to 3 calls per IP per 24h, signed receipts included). Get a free key at https://verify-api.dev/signup — no credit card required.
Input:
{
"claim": "Python 3.13 was released in October 2024."
}
Output:
{
"verdict": "supported",
"confidence": 0.99,
"source_url": "https://docs.python.org/3/whatsnew/3.13.html",
"exact_quote": "Python 3.13 was released on October 7, 2024.",
"reasoning": "Multiple authoritative sources confirm...",
"receipt": {
"jws": "eyJhbGci...",
"kid": "pQAd73zRp9Xq9Y5U"
}
}
Verdicts: supported, contradicted, unverifiable. Every supported/contradicted verdict comes with a JWS receipt signed by keys served at https://api.verify-api.dev/.well-known/jwks.json.
Why signed receipts?
Because "the AI checked" is not the same as "the AI verified." A signed receipt lets a downstream system — compliance auditor, user, another agent, a smart contract — cryptographically prove that a specific claim was verified against a specific source at a specific time by VerifyAPI's known public key. It's the difference between saying "trust me" and handing over a notarized document.
Pricing
- Free trial: no signup, no card. Limited to 3 calls per IP per 24h. Includes signed receipts.
- With API key: $0.02 per verified claim. Unverifiable / out-of-scope calls are free (you don't pay for "I couldn't find enough evidence").
- Freshness tiers: standard verification $0.02, real-time (fresh-fetch) $0.05.
- Auto top-up: save a card, set a threshold, keep flowing.
POST /v1/balance/autorefill.
Example use cases
LangChain / LlamaIndex agents: wrap verify_claim as a Tool. Have your agent call it before returning any factual answer.
Cursor / Cline coding agents: verify version numbers, API existence, deprecation status before writing imports.
Claude Desktop workflows: "Verify this quote is real before I put it in the deck."
Multi-agent systems: pass receipts between agents to prove groundedness up the chain.
Compliance-sensitive automation: keep the JWS receipts as audit trail for every factual decision the agent made.
Environment variables
| Variable | Required | Default | Description |
|---|
VERIFYAPI_API_KEY | No | (unset = trial) | Your VerifyAPI key (csk_live_...). Get one free at https://verify-api.dev/signup |
VERIFYAPI_BASE_URL | No | https://api.verify-api.dev | Override the API base URL. Useful for self-hosting or testing. |
Programmatic API (skip MCP, call directly)
curl -X POST https://api.verify-api.dev/v1/verify \
-H "Authorization: Bearer csk_live_..." \
-H "Content-Type: application/json" \
-d '{"claim": "Bitcoin ETFs were approved by the SEC in January 2024."}'
Full OpenAPI spec: https://api.verify-api.dev/openapi.json
x402 payment support built in — see https://verify-api.dev/agents.txt for the agent-native discovery manifest.
Links
Built by
Circuit Savers LLC — Wausau, Wisconsin.
License
MIT