CONNECT SYSTEM ONE

Connect System One.
One MCP URL.

Choose your agent and open a ready setup prompt. Verify your email and approve the connection in your browser. Then use hosted Code Mode to combine bounded Jev checks, or ask one direct question using evidence you supply.

Open hosted setup ↗Set up locally

QUICK SETUP

Add System One to your agent

Choose where you work. Open a ready install dialog in Cursor or VS Code, or let Codex and Claude Code add the MCP from a prepared prompt. You verify your email and approve access in your browser. After tool discovery, try sysone_code with a dependent set of checks.

Let Codex set it up

Open a prepared prompt. Codex adds the server and checks which tools are available.

Open in Codex ↗

The prompt contains an MCP address, never a credential. Review and send it in Codex.

Preview prompt

Help me connect System One MCP in Codex.

First check whether System One or system-one is already connected. Reuse it if it is.

If it is missing, add this remote MCP server:
codex mcp add system-one --url https://cloud.systemoneengine.com/mcp
If the sign-in page does not open, run codex mcp login system-one. I will verify my email and approve access in my browser. Never ask me to paste an email code, API key or access token into chat.

List the available System One tools and tell me what is ready or what I still need to do. Do not claim the connection works until discovery succeeds. Do not run a paid evaluation or retry a failed call automatically.

Or add it yourself

Run codex mcp add system-one --url https://cloud.systemoneengine.com/mcp in a terminal.
Complete browser sign-in. If needed, run codex mcp login system-one.
Start a new chat and ask Codex to list System One tools.

Opening an agent or copying a command does not complete sign-in. Approve access in your System One workspace.

Free early access needs no payment card or waitlist. Your verified account has free Jev access with daily usage limits. Hosted Code Mode has a separate daily execution limit. Local setup uses your own provider key and currently offers direct tools only.

Optional: choose a recipe selection

Customize the saved recipes your agent discovers, then publish the selection in your workspace. You can connect without this step. Enabled service tools can still accept custom questions; recipe selection does not change a connection's permissions.

6 recipes selected here

Off

Explore 35 more recipes

Select a recipe to include it in the selection you publish. Your connected agent can read that selection through sysone://recipes.

THIS SELECTION

Selection namePublish on your cloud MCP Connect with the default recipes instead →

This page keeps a draft in the browser. Publishing opens the hosted workspace, where you sign in and save. Your account has one published selection shared by its connections. Saving another draft replaces that selection. Until the first save, the full library is available.

Remote MCP URL

Add it in Cursor.

Cursor opens an install prompt for this remote MCP URL. Review it, then sign in with email and approve the connection.

Add to Cursor

If the prompt does not appear, merge this entry into your MCP settings and keep your other servers.

{
  "mcpServers": {
    "starter": {
      "url": "https://cloud.systemoneengine.com/mcp"
    }
  }
}

Cursor install links ↗

Add it in Claude Code.

Run this command, then open /mcp in Claude Code and authenticate in the browser. On claude.ai, add a custom connector in Settings when that account allows a remote MCP URL.

claude mcp add --transport http starter https://cloud.systemoneengine.com/mcp

Claude Code MCP guide ↗

Register it in Codex.

Add the remote server, then complete email sign-in and review the permissions in the browser.

codex mcp add starter --url https://cloud.systemoneengine.com/mcp
codex mcp login starter

Codex MCP guide ↗

Agent prompt

Help me use System One MCP for these decisions:
- Find the code responsible for a form submitting twice. (recipe next-tool)
- Search found several files. Which ones explain this bug? (recipe context-relevance)
- Does this tool output support the claim that the release is live? (recipe evidence-check)
- Choose a calm palette for a coastal reading app. (recipe palette-match)
- Find a compact desk lamp with warm light and no subscription. (recipe item-match)
- The service is running, but requests still fail. What should we inspect next? (recipe diagnostic-test). The person named this selection "Starter".

Reuse an available System One connection. Do not install a duplicate. Search discoverable tools for System One or sysone only if none are visible.

If no connection is available, help me add the remote System One MCP at https://cloud.systemoneengine.com/mcp using this agent's supported MCP settings. Setup instructions: https://systemoneengine.com/connect/ I will verify my email and approve OAuth in my browser. Do not request my email code, provider key or access token in chat. Do not claim you connected until a tool call succeeds. If this account cannot add a custom MCP, explain the limitation and offer a supported client or the local setup.

Choose one bounded job when it helps: sysone_check tests a claim against supplied evidence, sysone_find finds an answer in supplied excerpts, and sysone_select compares a short list. Use sysone_run for a fitting recipe. Prefer these ids: next-tool, context-relevance, evidence-check, palette-match, item-match, diagnostic-test. Use sysone_decide for a custom set of typed questions. When an earlier result determines a later question, use hosted sysone_code if this connection exposes it: write an async JavaScript function using its granted jev.* methods, branch on value fields, and return only the findings needed for this task. Batch independent questions over one state with jev.evaluate. Use a direct tool for one check. Send the minimum relevant evidence. Do not call Jev to confirm an answer you already reached from evidence you read. Use code for exact rules. Retain source evidence and uncertainty. A model answer never grants permission to act. Do not retry a failed evaluation automatically.

Report the decision, its limits, and any measured latency/usage. Do not invent token savings or treat a lower model probability as calibrated confidence.

Open your hosted dashboard →

Free early access has daily usage limits shared by your connections. A copied command is not a completed sign-in.

Connect System One.
One MCP URL.

Add System One to your agent

Let Codex set it up

Let Claude Code set it up

Add it in Cursor

Add it in VS Code

Add a connector in Claude

Other agents with remote MCP

Optional: choose a recipe selection

Watch the calls after you connect.

Connect System One.One MCP URL.

Add System One to your agent

Let Codex set it up

Let Claude Code set it up

Add it in Cursor

Add it in VS Code

Add a connector in Claude

Other agents with remote MCP

Optional: choose a recipe selection

Watch the calls after you connect.

Connect System One.
One MCP URL.