argus-decision-mcp

Keeping Judgment Human.

Your AI gives you an answer. Argus gives you a receipt — and checks it against reality on the date you set.

Argus is an MCP server for decision accountability. Instead of grading your choices, it makes you write down a falsifiable prediction and a check-by date, then brings you back on that date to compare what you predicted against what actually happened. The artifact it produces — a Judgment Receipt — carries one line no other AI tool will: AI VERDICT … NONE. The model never graded you. Reality did.

Runs on any MCP host that supports local stdio servers — Claude Desktop, Claude Code, and other clients that launch a local process. (Remote-only connectors that require an HTTP transport aren't supported yet.)

Install (Claude Code): claude mcp add argus "--" npx -y argus-decision-mcp — zero config, your ledger lives in ~/.argus. Then just talk to your AI; see your first receipt below.

┌─ ARGUS · JUDGMENT RECEIPT ────────────────────────────────┐
  Prediction saved 2026-04-02      Result recorded 2026-06-30

  THE REAL QUESTION
    Can we cut over without a maintenance window users notice?
  THE UNVERIFIED ASSUMPTION
    The index rebuild fits inside the replication lag budget.
  HUMAN-ONLY CALL   Whether a 5-minute blip is acceptable.
  …made by          Me. (not the model)

  YOU PREDICTED   "Cutover downtime is under 5 minutes"   (check-by 2026-06-30)
  WHAT HAPPENED   Cutover took 3 minutes, no customer reports.
  ─────────────────────────────────────────────────────────
  AI VERDICT ON THIS DECISION ······················  NONE
  The model never graded you. Reality did.
└──────────────────────────  argus · prediction → reality ─┘

Why it's different

It is not a receipt of what your agent did. A growing set of tools now log an AI coding run — prompt captured, files touched, checkpoint saved, replay path written down. That receipt is about the machine's actions over one run. Argus receipts something no run-logger can: your judgment call, in your own words, opened again on a date you set and settled against reality — not against a model's opinion, and not against a diff. Machine-action receipts and judgment receipts are different primitives; you can keep both.

Most decision tools compete on a better answer, a score, a confidence. Argus does the opposite, and the opposite is enforced structurally, not promised in prose:

• There is no verdict tool. The model cannot grade your decision because no argus_verdict / argus_score tool exists to call. grep dist/ and see.
• You can't record a result without a saved prediction. argus_resolve hard-errors without a prior argus_predict — "no judgment without a falsifiable prediction" is a precondition, not a suggestion.
• State is the ledger, not a flag. A decision's status is the fold of an append-only event log, so it can't be faked by calling tools out of order.

Install

Claude Code:

claude mcp add argus "--" npx -y argus-decision-mcp

Or add to your host's MCP config. Zero config works: with no env at all, your ledger lives in ~/.argus. That's all most people need — jump to your first receipt. The block below is only for per-project ledgers, account sync, or non–Claude-Code hosts.

Claude Code (expands ${CLAUDE_PROJECT_DIR}, so a per-project ledger works):

{
  "mcpServers": {
    "argus": {
      "command": "npx",
      "args": ["-y", "argus-decision-mcp"],
      "env": {
        // OPTIONAL — per-project ledger. Omit entirely to use ~/.argus.
        "ARGUS_DIR": "${CLAUDE_PROJECT_DIR}/.argus",
        // OPTIONAL — connect to your Argus account so saved predictions get an
        // email at their check-by date and show up in the web dashboard. Issue
        // the token at https://argus.voyage (Settings → sync token). Leave it
        // unset to stay fully local (the privacy-preserving default).
        "ARGUS_TOKEN": "argus_pat_…",
        // OPTIONAL — the timezone that decides when a check-by date becomes
        // "today". Unset = your machine's local timezone (usually right).
        // Set it only if your machine's clock zone isn't where you live:
        "ARGUS_TZ": "Asia/Seoul",
        // OPTIONAL — opt in to anonymous usage telemetry (OFF by default). Sends
        // a random install id + which tool ran + version/platform; never your
        // decisions or token. Honors DO_NOT_TRACK. See SECURITY.md → Telemetry.
        "ARGUS_TELEMETRY": "1"
        // "ARGUS_API_URL": "https://argus.voyage"  // override only for self-host
      }
    }
  }
}

Claude Desktop does not expand ${...} variables — a literal ${CLAUDE_PROJECT_DIR} would fail on every call (Argus names this error when it happens). Either omit ARGUS_DIR (→ ~/.argus) or use an absolute path:

// macOS
"env": { "ARGUS_DIR": "/Users/you/.argus" }
// Windows — also note the command form below
"env": { "ARGUS_DIR": "C:\\Users\\you\\.argus" }

Windows hosts often can't launch bare npx (it's npx.cmd). If the server fails to start, use:

{
  "command": "cmd",
  "args": ["/c", "npx", "-y", "argus-decision-mcp"]
}

argus_dir is optional on every tool: omit it and it resolves from ARGUS_DIR, then falls back to ~/.argus. A per-call argus_dir still wins — so Argus works on any host even when env-variable interpolation doesn't.

Your first receipt (2 minutes)

You never call these tools by name. Once the server is connected, you just talk to your AI in plain language and it calls the right tool for you. One full loop — from saving a prediction to recording what reality did — looks like this:

1 · Save a prediction — before you commit to a decision, tell your AI:

You: "I'm shipping the new onboarding flow next week. Save this prediction: signups go up at least 10% by the end of the month."

Argus records your predicate and a check-by date. Nothing is scored — it's a prediction against reality, not a grade from the model.

2 · Update a fact (optional, any time before the date) — if a fact your decision leaned on might have moved:

You: "Update the signup number behind my onboarding decision. Has it changed since I saved the prediction?"

Argus compares the new number to the baseline and tells you if it drifted. It returns the handle — whether to revisit the decision stays your call.

3 · Record the result on the check-by date — when the date arrives:

You: "Record the result of my onboarding prediction. Signups went up 14%."

Argus prints the Judgment Receipt at the top of this page — with AI VERDICT … NONE. You made the call; the record contains what reality did, not a model's grade.

That's the whole spine. Everything below is detail on top of these three steps.

The everyday loop

Argus now exposes six tools named for the job they do. You do not initialize it first, choose a ritual, or learn its internal state machine. The first useful call creates the local record automatically.

For most decisions the loop is simply:

1. argus_capture — capture a decision's premises and open questions, in your own words.
2. argus_predict — make a falsifiable prediction and the date reality can answer it.
3. argus_check_in — see only what needs attention now.
4. argus_resolve — record what actually happened, without a score or verdict.

argus_patterns reads what is already on record — past decisions and how often your predictions held. argus_settings handles the few preferences and account-sync controls a user may need.

| Tool | What it does | |------|--------------| | argus_capture | Captures one decision's premises and open questions in the user's own words, without deciding for you. Its actions add assumptions and open questions, record your answer, update an external fact, change an untested prediction, or close a decision that no longer needs an outcome. | | argus_predict | Makes a falsifiable prediction (predicate + check_by) in the user's words. An Argus-drafted line is marked honestly and shown as a one-tap draft to keep, reword, or skip. | | argus_check_in | Shows only predictions past their check date, external facts due for an update, and open questions due for reconsideration. If nothing needs attention, it stops. | | argus_resolve | Records what actually happened and issues the Judgment Receipt. Reality supplies the outcome; Argus does not grade it. | | argus_patterns | Reads active decisions, all records, one Judgment Receipt, one decision's context, or the accumulated frequency of outcomes. Read-only. | | argus_settings | Reads or updates language, quiet reminders, opt-in premise sync, and explicit account sync. Initialization is automatic. |

Living premises

The receipt's sharpest line — THE UNVERIFIED ASSUMPTION — used to be written once when a prediction was saved and then go dead. Now it's a tracked object: name the premises a decision rests on, correct the ones the model got wrong (your edit is part of the record), and re-check the load-bearing external facts against reality while the bet is still open. When a rate hike breaks the premise under three of your decisions, that's one re-check, not three.

Honest limits, stated up front: an MCP server is passive — nothing wakes it between saving a prediction and recording its result. Every tool response can carry a quiet due_note, argus_check_in reports due items, and the single argus://attention resource lets capable hosts auto-inject what needs attention. No separate prompt ritual is advertised. Anything more periodic (cron, reminders) belongs to your host or habits, not this server. A premise that never gets re-checked shows up honestly as never re-checked — Argus does not pretend liveness.

Data

Everything is local, under .argus/ in your project (gitignored by default) — an append-only ledger.jsonl you own: plain JSON lines, no lock-in, receipts render to shareable text. No telemetry by default. The only network call Argus makes out of the box is the opt-in account sync: if — and only if — you set ARGUS_TOKEN, a saved prediction or recorded result is POSTed to your own Argus account so it can email you at its check-by date. Separately, you can opt in to anonymous usage telemetry with ARGUS_TELEMETRY=1 (a random install id + which tool ran + version/platform, never your decisions or token; honors DO_NOT_TRACK) — see SECURITY.md. Premise data stays on your machine by default — it is not part of the sync payload. There is exactly one switch that changes this: argus_settings with action:"update" and premise_sync:true (off unless you set it) sends a saved decision's monitored premises along, so your account's autonomous premise-watch can re-check them against reality and email you when one materially moves. Unset the token and Argus never touches the network. See SECURITY.md.

Measured

The structural claims are tested, not asserted — npm test runs deterministic gates (no verdict tool exists, recording a result before a prediction is saved is refused, path traversal blocked, receipts carry ai_verdict: null). A model-in-the-loop spine eval (npm run eval, 12 scenarios, opus judge) measured, on current Sonnet and Haiku:

| | over-fire on flat cases | crux carries a lean | free-text verdict leak | |---|---|---|---| | Sonnet 4.6 | 0 / 6 | 0 / 12 | 0 / 12 | | Haiku 4.5 | 0 / 6 | 0 / 12 | 1 / 12 |

Tool-surface verdict leak is 0 by construction. The one free-text leak (Haiku, on "salad or sandwich") is exactly the limit below — a model can still type an opinion in chat, and Argus reports that number rather than hiding it.

An honest limit

Argus removes the verdict from its tool surface and walls off settling a bet that was never made. It cannot stop a model from typing an opinion in free chat between tool calls — no MCP server can. So Argus doesn't claim "zero judgment"; it surfaces one question, names any faint lean as a known limit, and lets reality do the grading. zero judgment is an asymptote, disclosed — not a badge.

Develop

npm install
npm run build
npm test          # deterministic spine + state-machine + path-safety gates
npx @modelcontextprotocol/inspector node dist/index.js

Links

• Web app (nothing to install): https://argus.voyage
• Source & issues: https://github.com/commet/Argus
• License: MIT.