Jev

Launching soon. This page is live before Jev’s public go-live. Today, signing in works, but Jev currently accepts only tester accounts — so outside of a tester account, sign-in completes and the first call then fails.

What Jev is

Jev is TypeSafe’s guardrail model, hosted by Viorant and served to any MCP client as a remote connector at https://jev.viorant.io/mcp. It gives an agent six tools it can call mid-run:

jev_verify — checks claims against evidence text and returns a verdict per claim (verified / contradicted / unsupported) with a confidence.
jev_screen — screens fetched or external text before an agent reads it, for prompt injection and substance, and (with a stated purpose) task relevance.
jev_find — ranks candidates against a plain-language query; semantic search, no embeddings needed.
jev_noul — returns a calibrated probability for each of a batch of stated propositions.
jev_choice — asks one caller-authored multiple-choice question and returns the chosen option with a probability per option.
jev_score — asks one caller-authored question scored against an ordered rubric and returns the expected score with a probability per level.

Sign-in uses your existing Viorant account — there is no separate Jev account.

Connect from an MCP client

Jev is a standard remote MCP server with OAuth. Each client below gets its own config. Tested means a run against that exact config, on this page, by a Viorant tester, is on record. Everything else is Untested — the config is correct per that client’s own documented remote-MCP format, but no one has run it against Jev yet.

Claude Code — Untested

claude mcp add --transport http jev https://jev.viorant.io/mcp

Then in a Claude Code session, run /mcp and choose Authenticate for jev.

A Jev sign-in was run from Claude Code on 2026-10-05, but with a hand-built PKCE client and claude -p — not the claude mcp add / /mcp → Authenticate commands shown above. Since that isn’t a run of what this page publishes, it’s marked Untested rather than claimed on mismatched evidence.

Cursor — Untested

.cursor/mcp.json

{
  "mcpServers": {
    "jev": {
      "url": "https://jev.viorant.io/mcp"
    }
  }
}

VS Code — Untested

.vscode/mcp.json

{
  "servers": {
    "jev": {
      "type": "http",
      "url": "https://jev.viorant.io/mcp"
    }
  }
}

Windsurf — Untested

mcp_config.json

{
  "mcpServers": {
    "jev": {
      "serverUrl": "https://jev.viorant.io/mcp"
    }
  }
}

Codex CLI — Untested

config.toml

[mcp_servers.jev]
url = "https://jev.viorant.io/mcp"

Gemini CLI — Untested

settings.json

{
  "mcpServers": {
    "jev": {
      "httpUrl": "https://jev.viorant.io/mcp"
    }
  }
}

Any other MCP client — Untested

Jev follows the standard remote-MCP discovery and dynamic client registration flow, so any compliant client can add it from the URL alone. As supporting evidence that the endpoints are live (not a tested marker — no client’s exact config has been run against them), here is discovery, DCR metadata, and an unauthenticated call, each run fresh against https://jev.viorant.io:

$ curl -i https://jev.viorant.io/.well-known/oauth-protected-resource/mcp
HTTP/2 200
content-type: application/json

{"resource":"https://jev.viorant.io/mcp","authorization_servers":["https://jev.viorant.io"],"scopes_supported":["jev:verify","jev:screen","jev:find"],"bearer_methods_supported":["header"],"resource_name":"Viorant Jev"}

$ curl -i https://jev.viorant.io/.well-known/oauth-authorization-server
HTTP/2 200
content-type: application/json

{"issuer":"https://jev.viorant.io","authorization_endpoint":"https://jev.viorant.io/authorize","token_endpoint":"https://jev.viorant.io/token","protected_resources":["https://jev.viorant.io/mcp"],"registration_endpoint":"https://jev.viorant.io/register", ...}

$ curl -i -X POST https://jev.viorant.io/mcp -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{}}'
HTTP/2 401
www-authenticate: Bearer realm="OAuth", resource_metadata="https://jev.viorant.io/.well-known/oauth-protected-resource/mcp", scope="jev:verify jev:screen jev:find"

A client that supports dynamic client registration can POST to registration_endpoint and complete the standard authorization-code + PKCE flow from there with no manual app setup.

From a deployed `vio` agent

Declare Jev like any other OAuth connector, with all six tools:

requires:
  - connector: https://jev.viorant.io/mcp
    scopes: []
    auth: oauth
    kind: connector
    tools:
      - jev_verify
      - jev_screen
      - jev_find
      - jev_noul
      - jev_choice
      - jev_score

Then:

vio deploy --target viorant_cloud
vio connect <id> .

vio connect opens a browser for sign-in, then pushes the credentials.

Tested (prod, by a tester account, 2026-10-06). This exact recipe ran end to end: a deploy with the connector block above, vio connect <id> . → sign-in → Credentials pushed, then one jev_verify call returning ok: true in 2344 ms, with the run reaching run.completed at 12.6 s.Two caveats carried over from that run: it was unmetered, since it ran on a tester account — a non-tester, paid-fallback run is still needed after go-live — and it used a hand-wired recipe rather than a built-in one, because vio 1.0.2, which bakes a Jev recipe in, is unpublished as of this run. The commands above are written to work on the released vio 1.0.1.

Cost

Jev is paid from your Viorant credits: 100 credits per 1M Jev tokens (input tokens). There’s no separate Jev allowance. Every new Viorant account starts with 2,500 free credits, enough for up to 25M Jev tokens if you spend them only on Jev. It’s one balance: credits you spend on agents or models elsewhere in Viorant come out of the same 2,500. Every Jev tool result carries your remaining balance in a top-level allowance_remaining field (not nested under usage):

"unlimited (tester)": your account is a Jev tester, and nothing is metered.
"<n> credits (Viorant credits)": your Viorant credit balance after the call.

Limits and errors

Jev returns these as MCP tool-error text — never as an HTTP status code. Each comes back with one of these exact messages:

Case	Message
Account disabled	`This Viorant account cannot use Jev.`
Rate limit (120 calls/60s)	`Too many Jev calls. Retry after 60 seconds.`
Daily cap (20,000 calls/day)	`Too many Jev calls today. Retry after 24 hours.`
Input over the per-call limit (24,000 tokens)	`Input is over the 24,000-token limit for one Jev call.`
Jev paused for maintenance	`Jev is paused for maintenance. Try again later.`
Jev’s overall budget reached	`Jev has reached its budget. Try again later.`
Wallet balance too low	`Your Viorant credits are too low for this Jev call. Top up in Viorant Hub.`
Paid fallback unavailable	`Viorant credits are unavailable right now`
Free accounts at capacity	`Jev is full for free accounts right now. Upgrade to a paid plan to use it.`
Jev at capacity	`Jev is full right now.`

Terms

Using Jev is covered by Viorant’s Terms of Service.

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What Jev is

Connect from an MCP client

Claude Code — Untested

Cursor — Untested

VS Code — Untested

Windsurf — Untested

Codex CLI — Untested

Gemini CLI — Untested

Any other MCP client — Untested

From a deployed `vio` agent

Cost

Limits and errors

Terms

​What Jev is

​Connect from an MCP client

​Claude Code — Untested

​Cursor — Untested

​VS Code — Untested

​Windsurf — Untested

​Codex CLI — Untested

​Gemini CLI — Untested

​Any other MCP client — Untested

​From a deployed vio agent

​Cost

​Limits and errors

​Terms

What Jev is

Connect from an MCP client

Claude Code — Untested

Cursor — Untested

VS Code — Untested

Windsurf — Untested

Codex CLI — Untested

Gemini CLI — Untested

Any other MCP client — Untested

From a deployed `vio` agent

Cost

Limits and errors

Terms