Lenz Fact Check

What is Lenz Fact Check?

Lenz Fact Check is a remote MCP server that takes a factual claim and runs it through a multi-model pipeline (framing, research, debate, panel review, conclusion) against independent sources on the open web, returning a verdict with a directional confidence level. It is designed for any MCP client and complements retrieval or groundedness checkers.

How to use Lenz Fact Check?

No installation is required. Point your MCP client to https://lenz.io/mcp with transport type http. Authentication is via OAuth or a free Lenz API key (Authorization: Bearer lenz_…). Use tools like assess for a fast verdict (~5–10s) or verify for a deep investigation (~90s) that returns a task_id to poll.

Key features of Lenz Fact Check

• Multi-model pipeline (framing → research → debate → panel review → conclusion)
• Fast verdict via 3-model panel (assess) in ~5–10 seconds
• Deep investigation (verify) for high-stakes claims in ~90 seconds
• Follow-up grounded questions (ask) on completed verifications
• Resolves multi-claim or clarification interrupts (select)
• Remote, hosted service – no local install needed

Use cases of Lenz Fact Check

• Verifying factual claims against independent web sources without relying on the model’s training data
• Performing quick sanity checks on statements during research or content generation
• Conducting thorough, multi-step investigations for high-stakes or sensitive claims
• Asking clarifying follow-up questions after a completed verification
• Monitoring API usage and remaining quota via the check_usage tool

FAQ from Lenz Fact Check

How do I connect my MCP client to Lenz Fact Check?

Point your client to https://lenz.io/mcp with transport type http and use OAuth or a free Lenz API key (Authorization: Bearer lenz_…).

What kind of verdicts does it return?

Verdicts are directional, not absolute – confidence is bucketed and includes a caveat. The assess tool returns a quick verdict; verify returns a more detailed investigation.

How fast are the different fact-checking modes?

assess typically takes ~5–10 seconds, while verify takes about 90 seconds and returns a task_id that can be polled with get_verification.

Does Lenz Fact Check require any local installation?

No – it is a remote (hosted) MCP server. No software or dependencies need to be installed.

What authentication options are available?

You can use OAuth (no key) or obtain a free Lenz API key from lenz.io/api-integration and pass it as Authorization: Bearer lenz_….