Verify API MCP Server

MCP server for Verify API: a pay-per-call verification service that gives agents a fast, structured, evidence-backed yes/no/unknown on claims they'd otherwise guess at.

Stop your agent from citing things that don't exist, or installing things that shouldn't. Three tools, one answer each, evidence attached.

Tools

• verify_citation -- does a citation exist, is it retracted, and does the given title/authors/year/journal match the canonical record? Checked against Crossref (includes Retraction Watch data) with OpenAlex as a fallback.
• verify_url -- does a URL resolve, what's the final status and redirect chain, is it archived on the Wayback Machine, and (optionally) does expected text appear on the page?
• verify_package -- does an npm/PyPI/crates.io package exist, is it deprecated or yanked, and does it have known vulnerabilities? Checked against the registry plus OSV.dev advisories. Catches an agent installing a hallucinated or squatted package name.

Every response includes a verdict (confirmed / contradicted / unknown), the individual checks that were run, and evidence with source URLs so a human can verify the answer themselves. unknown is a valid, honest answer -- this server never guesses to avoid it.

Install

pip install verify-api-mcp

Configure

Get an API key by subscribing to a plan at goodsong.dev/#pricing (Solo, $15/mo, or Team, $49/mo) -- the key is issued immediately on the checkout success page. There's no free tier, but no commitment either: the same API also accepts x402 pay-per-call (no key, no account, $0.005/call) if you'd rather try it that way first -- this MCP server specifically needs a key, since x402 requires a wallet most MCP clients don't have.

Then add your key to your MCP client's config (e.g. mcp.json):

{
  "mcpServers": {
    "verify-api": {
      "command": "verify-api-mcp",
      "env": {
        "VERIFY_API_KEY": "vk_..."
      }
    }
  }
}

VERIFY_API_URL defaults to https://goodsong.dev and only needs to be set if you're pointing at a different deployment.

License

MIT