LiveVariant

Build, inspect and read adaptive A/B tests.

CommunityDegradedNo sign-inGlobalFreeRead-only

What it can do

    What data it sees

    Do you need an account

    No: the server works without sign-in

    Build, inspect and read adaptive A/B tests. Config travels in the URL; no account or API key needed.

    How to connect

    How to connect LiveVariant to Claude

    The server address to paste into Claude settings:

    https://livevariant.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 LiveVariant to ChatGPT

    The server address to paste into ChatGPT settings:

    https://livevariant.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 LiveVariant to Cursor

    The server address to paste into Cursor settings:

    https://livevariant.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 (9)

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

    build_testCreates a LiveVariant test and returns every URL needed to run it, plus a freshly generated stats secret. Pass `variants` to test one element, or `slots` to test several at once (hero image AND call-to-action, say). With slots the test optimizes the COMBINATION: one model learns how the elements interact, which two separate tests structurally cannot see. There is no algorithm to pick either way; every test runs the same joint model, sized from its shape. By default, nothing is registered anywhere: the config IS the test, encoded into the URLs, and the test's identity is a hash of it. Pass `publishableKey` on an account-enabled deployment to also register the new test to that key's organization, so it appears under My tests; the config and URLs are still the test, and registration failure is returned as a warning rather than failing the build. Editing a variant later produces a DIFFERENT test with its own empty history, which is usually what you want per campaign but is worth saying out loud to whoever you are building this for. The stats secret is returned once and never again. Only its hash goes into the config, so nobody, including this service, can recover it. Give it to the person who will read the results.
    inspect_testDecodes a test and describes it: slots, variants, context, and whether it can be served by redirect. Also lints it for the mistakes that only show up once a campaign is out, such as an email test whose context comes from geo (which a mail proxy answers about itself). Use this before sending anything, and to answer 'what is this link?'.
    generate_priorsTakes YOUR estimate of how each variant will perform and converts it into the prior the model starts from, so a test does not spend its first visitors rediscovering what you already suspect. You supply the guess; this does the arithmetic and the capping. That capping is the point: a prior is expressed as pseudo-observations, and it is deliberately held weak enough that real data overrides it quickly. The response says exactly how many real visitors per variant it takes to wash your guess out, so you can judge whether you have been too confident. Being wrong here costs a little early traffic, not the test. Priors are outside the identity hash, so the test keeps its id, its URLs and any history it already has. Pass `when` to make the belief hold for ONE segment only ("image B is the one for the blue segment"). Without it the belief is about every visitor, which is a different and much stronger claim.
    get_statsFetches a test's results and works out what they mean. Alongside the raw counts it returns the probability that each combination is genuinely best and the expected cost of stopping now and keeping the leader. Use those rather than comparing conversion rates by eye: a variant ahead 2/10 to 1/10 looks twice as good and is very close to a coin flip, and that mistake is the single most common way an A/B test gets called wrong. Multi-slot tests also report per-slot marginals: how each variant did across every combination it appeared in. Needs the stats secret. If you have the manage URL, its #fragment IS the secret and it will be used automatically.
    get_test_statusReports what the deployment's registry knows about a test: whether it is claimed into an account (and by which organization), and whether each redirect destination is a verified domain. Unverified destinations work, but visitors see a 'Redirecting you to…' continue screen first. When you see verified: false, tell the user to verify the domain under Settings on the dashboard; the three ways are a DNS TXT record, serving the well-known file, or having the SDK tag with their publishable key live in the site's source. If the test is unclaimed, remind them the manage URL claims it in one click when opened signed in. Requires the test's stats secret, the same as get_stats. A manage URL's #fragment is used automatically.
    list_testsLists tests registered to the signed-in account, newest first, with cursor pagination and an optional case-insensitive name filter. Only exists on deployments with accounts, and only answers for an identified caller: unlike every other tool, WHOSE tests these are cannot be expressed as an argument. Each entry carries the encoded config, which inspect_test and get_stats accept directly.
    register_testRegisters a test you built earlier to the organization a publishable key belongs to, so it shows under My tests and its stats are readable from the dashboard without the secret. Use this only when the user provides both the test's stats secret and a publishable key for an organization they administer. The stats secret must match the hash inside the config, and the publishable key identifies the organization to register into. Prefer passing publishableKey to build_test directly: it registers at creation in one step. Keyless tests cannot be registered this way (nothing to prove with); they register through the tag on a verified domain. The organization can remove a listing from its dashboard (the test itself keeps serving).
    upload_imageUploads an image to the deployment's asset store and returns its URL, for use as a variant's `image` (email tests) or `url`. The returned URL is deliberately not fetchable on its own: assets are only served with a short-lived signature that the serve endpoints mint per request, so uploading here does not create free static hosting. Use `previewUrl` (valid for an hour) to check what was stored. Storage is content-addressed: the id is the sha256 of the bytes, so uploading the same image twice is harmless and returns the same URL. Raster images only; SVG is refused because it can carry scripts. Not every deployment enables asset hosting, and this tool says so plainly when yours does not.
    variant_briefReturns the constraints to write or generate test variants against, for email or web, plus the rules that decide whether a test can be read at all once it runs. The one that matters most: one idea per slot. To vary two elements, give the test two slots and let it learn the combination, rather than bundling both changes into one variant and never learning which half worked. Ask for this before drafting variants, then produce them yourself against what it returns.