Xyntherium Verify

For developers

Send the question, the answer your model drafted and the passages it was given. Verify splits the answer into claims, quotes the passage behind each one, and flags any claim that contradicts the sources or drops a condition they attach: a deadline, an exception, a limit, an eligibility rule. Ship the answer only when release_recommendation is allow.

One free tier for everything: 1,000 checks a month, no card. API, MCP and Gate checks all draw from the same allowance. Get an API key →

The API

One request, one JSON response with a verdict and quoted evidence for every claim. TypeScript and Python clients are thin wrappers over it.

curl https://xyntherium.com/v1/verify \
  -H "Authorization: Bearer $XYN_API_KEY" -H "Content-Type: application/json" \
  -d '{"question":"Can I get a refund?",
       "answer":"Refunds are available within 30 days.",
       "sources":[{"id":"returns","text":"Refunds are available within 30 days for unopened items with proof of purchase."}]}'
API docs →Limits and errors →Try it in the browser →

verify-mcp

The same check as an MCP tool, verify_answer, so an assistant checks a drafted answer against the documents in the conversation before it replies. It is read-only and changes nothing. Hosted at https://www.xyntherium.com/mcp (Streamable HTTP, protocol 2026-07-28 and 2025-11-25). For Claude, a plugin adds a skill that knows when to call it and when not: /plugin marketplace add augustbrookz/verify-gate.

Setup for Claude, Cursor and VS Code →The launch post, with a side-by-side →

Verify GateCLI on npm soon

A GitHub Action for teams that keep approved answers next to the documents they come from. When a pull request changes a document, Gate re-checks the saved answers against the new text, comments with the ones that no longer hold and the exact words that changed, and writes SARIF and a signed ledger record of the run. Formatting-only edits pass. It starts in report-only mode, so it never blocks a merge until you choose to. The Action is public now (uses: augustbrookz/verify-gate@v0); the npx @xyntherium/verify-cli init installer ships with the npm packages.

github.com/augustbrookz/verify-gate →A real run: a refund window changes from 30 to 14 days →

Four demos you can reproduce

  1. Refund: unopened items and proof of purchase · the answer drops both conditions; verify_answer names them
  2. Tariff: the HTS revision in force · an answer uses the +25% rate of an older revision; the revision in force says +50%
  3. Medicare: the LCD text · a CGM coverage answer drops the documentation requirement in LCD L33822
  4. Gate: a refund document changes · the window goes from 30 to 14 days and the saved answer that says 30 is flagged

Verdicts describe whether the supplied passages support each claim. They do not establish whether any claim is true in the world. Not legal advice.