agenticrail-mcp

A Model Context Protocol server that exposes the live AgenticRail enforcement gate to any MCP client as two tools.

AgenticRail is a deterministic enforcement layer for AI agents: it holds an agent to its declared step order, refuses replays and skipped steps, and seals each completed sequence with a signed receipt. This server is the MCP adapter in front of it.

In the words the problem usually gets asked in: it is a policy enforcement point for AI agent tool calls. It catches skipped steps and procedural hallucination (an agent reporting success on a step that never ran) by refusing the out-of-order step before it runs, and every decision, ALLOW or DENY, becomes a tamper-evident audit trail entry.

Endpoint: https://mcp.agenticrail.nz/ (Streamable HTTP, stateless) Protocol: 2026-07-28 — the revision that retired the initialize exchange and Mcp-Session-Id. This server was built stateless with neither, so it needed no migration. initialize is still answered for older clients. Registry: nz.agenticrail/gate on the official MCP registry

Tools

Tool	What it does	Calls
evaluate_step	ALLOW/DENY a single agent step before it runs; seals a signed receipt	POST https://api.agenticrail.nz/v1/evaluate
verify_receipt	Fetch a sequence's verification report; confirm the receipt chain is intact	POST https://report.agenticrail.nz/report

Call evaluate_step before running each step of a sequence, and do not run a step the gate DENYs.

A DENY tells you how to fix it

Every refusal carries its own remedy in the response envelope — unsigned, DENY-only, because it describes the sequence's state now rather than the decision that was made:

refusal	what comes back
ACTION_NOT_ALLOWED	allowed_action_types — exactly what this step would have accepted
SEQUENCE_VIOLATION	next_expected_step — the step the sequence is waiting for
STEP_ORDER_MISMATCH	locked_step_order — the order this sequence was locked to on its first call
UNKNOWN_STEP	expected_step_order + step_order_source (caller or msmd_spine)

action_type is an enum of exactly eight values, and each step accepts only a subset. The enum in the tool schema is a hint, not a control — it binds only a client that validates its own arguments, and an invented verb is by far the most common first refusal: READ, QUERY, TOOL_CALL, LOOKUP, EXECUTE and the like are not action types, however well they describe your step. The gate is the control. When it refuses, allowed_action_types comes back carrying the ones this step would have taken.

A refused call locks nothing. A denial is answered before the sequence store is written to, so the run is not spoiled: the call was wrong, not the sequence. Correct the field the denial names and send the step again. The lock is set only by actually sending a step_order on a call that is allowed; from then on that list is enforced and a different one is refused with STEP_ORDER_MISMATCH. Omitting step_order sets no lock at all — it means only that this call is judged against the built-in MSMD spine, whose step names are almost certainly not yours.

So if your process has its own step names, send step_order with those names and the gate will enforce your order instead. One step is a valid sequence.

Connect

In Claude Code:

# zero config — uses the public demo key
claude mcp add --transport http agenticrail https://mcp.agenticrail.nz/

# with your own key
claude mcp add --transport http agenticrail https://mcp.agenticrail.nz/ \
  --header "Authorization: Bearer <your-agenticrail-key>"

Any Streamable-HTTP MCP client works — point it at the URL.

Try it without installing anything

BASE=https://mcp.agenticrail.nz/

curl -s -X POST "$BASE" -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | jq .

# ⚠️ Use a sequence_id nobody else will pick. On the shared demo key the id is
# GLOBAL and sealing is PERMANENT — a fixed one in an example works once for one
# person on earth and returns SEALED_SEQUENCE for everyone after.
SEQ="mcp-smoke-$(date +%s)-$RANDOM"

curl -s -X POST "$BASE" -H 'content-type: application/json' \
  -d "{\"jsonrpc\":\"2.0\",\"id\":2,\"method\":\"tools/call\",\"params\":{
        \"name\":\"evaluate_step\",
        \"arguments\":{\"sequence_id\":\"$SEQ\",\"step\":\"intake\",
                       \"action_type\":\"CHECK_STATE\"}}}" | jq .

With no Authorization header the public demo key is used and your sequence_id comes back rewritten to demo-mcp-<your id> — demo- marks the public lane, mcp- marks it as anonymous MCP traffic. Use the id returned in the response from then on; the one you sent will not resolve. This is intended, not a leak.

A demo- sequence's report needs no key to read, so treat anything you send on it as public.

Design — read before changing

• Protocol adapter only. This worker holds no internal secrets and has no privileged path to the enforcement core. It calls the same public API an external caller uses, so the tool logic is decoupled from AgenticRail's internals and from the MCP transport version.
• Service bindings, not fetch. mcp.agenticrail.nz is on the same zone as api. and report., so a plain fetch() would be a same-zone loopback (Cloudflare error 1002). The bindings hit the identical public handlers — they are not an internal bypass.
• Stateless Streamable HTTP. No Mcp-Session-Id is issued or required; every POST is self-contained. The transport shell is handleRpc + the fetch handler — the only part a spec revision touches. The value-bearing calls (callEvaluate / callVerify) are plain HTTPS and don't change.
• GET / serves the discovery card; every other GET path 404s. POST is left permissive on purpose so a client that appends a path to the endpoint URL still works.
• A 404 on /.well-known/oauth-* is correct — it is how an MCP server says no auth required. agent.json, agent-card.json, x402 and ai-plugin.json are protocols this server does not implement; answering them would be a claim.

Deploy

npx wrangler deploy

Links

• Docs — https://agenticrail.nz/docs/
• Verify a sequence yourself — https://report.agenticrail.nz/report
• OpenAPI — https://agenticrail.nz/openapi.json
• Enforcement spec — https://agenticrail.nz/spec/

---

Operated by TUARA KURI LIMITED (NZBN 9429053582867), Hokianga, Aotearoa New Zealand.