Second Opinion

Adversarial verification for AI agents - pay an independent skeptic per verdict in USDC via x402.

CommunityOnlineNo sign-inGlobalFreeRead-only

What it can do

    What data it sees

    Do you need an account

    No: the server works without sign-in

    Adversarial verification for AI agents - pay an independent skeptic per verdict in USDC via x402.

    How to connect

    How to connect Second Opinion to Claude

    The server address to paste into Claude settings:

    https://secondopinionx402.com/mcp

    1. Open Claude (claude.ai or the desktop app).
    2. Go to Settings → Connectors.
    3. Click Add custom connector.
    4. Paste the server address copied below into Remote MCP server URL and click Add.
    5. In a chat, click + → Connectors and switch the new connector on.

    Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

    Authorization

    After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

    How to connect Second Opinion to ChatGPT

    The server address to paste into ChatGPT settings:

    https://secondopinionx402.com/mcp

    1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
    2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
    3. Open Settings → Connectors and click Create.
    4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
    5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
    6. In a new chat open + → Apps/Connectors and enable the connector.

    OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

    Authorization

    On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

    How to connect Second Opinion to Cursor

    The server address to paste into Cursor settings:

    https://secondopinionx402.com/mcp

    Fastest: click Open in Cursor below and confirm the prompt.

    Manually:

    1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
    2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
    3. Save the file. The server appears in the MCP list; authorize it there if asked.

    Authorization

    If the service needs sign-in, an authorize button appears next to the server in the MCP list.

    Server tool list (6)

    Raw names from tools/list. Only developers need these.

    second_opinion_quickIndependent reasoning-only check of a claim ($0.02, ~20s, no web research). Use for logic, internal consistency, and stable established knowledge (definitions, architectures, history, maths). Returns refuted/supported/inconclusive with calibrated confidence; honestly escalates to second_opinion_verify when the claim needs current-world research. Without a payment argument it returns an exact pay-per-call quote (no account, no API key).
    second_opinion_verifyIndependent adversarial verification with live web research ($0.20, ~60s). A separate AI attempts to refute the claim using current sources and returns a verdict with citations. Use before irreversible commitments that depend on current-world facts. Without a payment argument it returns an exact pay-per-call quote (no account, no API key).
    second_opinion_panelThree independent adversarial verifiers attack the claim through different lenses (evidence, logic, currency) and vote ($0.75, ~90s). Use for high-stakes or contested claims where a single check is not enough. Without a payment argument it returns an exact pay-per-call quote (no account, no API key).
    second_opinion_tryFREE TRIAL — no wallet, no payment, no account: the same quick reasoning-only check as second_opinion_quick, 3/day per caller (claims up to 500 chars; global daily cap applies). The trial verdict is unsigned — paid verdicts add an offline-verifiable Ed25519 receipt and live web research on the verify/panel tiers. Try the product here; use the paid tools for real work.
    second_opinion_resultFetch the verdict for a paid async job — polling is FREE and the verdict is already paid for. Returns status running|done|failed, with the full verdict when done.
    second_opinion_pricingFREE: current tiers, prices, and exact on-chain payment requirements (accepts) for every rail — Algorand, Base, Polygon, Solana. Use this to pre-build a payment, or to discover what a verification will cost before committing.