Argus Sentry

The Argus boundary for AI agents: one install that puts every tool call, skill, MCP action, and agent-to-agent request of any model through Argus, and makes executors refuse any action that lacks an Argus-signed capability token.

The four capabilities

1. Enforcement - every agent action evaluated against the operator's policy before it executes, with typed reason codes for every block.
2. Evidence - every decision signed into a tamper-evident Merkle + Ed25519 chain, verifiable offline with argus evidence verify.
3. Abstention - graded authority (full, scaled, safe-halt) instead of binary allow or deny, and INCONCLUSIVE fail-closed instead of a guess.
4. The Record - a signed deliberation record per action: what the agent proposed, what the gate saw, and what happened.

Install

pip install argus-sentry

Requires the Argus SDK v0.8 line (argus>=0.8) and Python 3.10 or newer.

Quickstart

Gate an MCP server in one command:

python -m argus_sentry.mcp.gateway \
  --server-id filesystem \
  --policy policy.txt \
  --policy-signer platform_policy_key_1 --policy-key <hex public key> \
  --class-map class_map.json \
  -- npx -y @modelcontextprotocol/server-filesystem /workspace

Wrap the server with token verification:

python -m argus_sentry.mcp.middleware \
  --server-id filesystem \
  --key-list key_list.bin \
  -- npx -y @modelcontextprotocol/server-filesystem /workspace

Model middleware:

from argus_sentry.adapters.model import ModelGate, ModelToolCall

gate = ModelGate(core)  # core: a SentryCore with prefix "model"
outcome = gate.evaluate(ModelToolCall("openai", "delete_all_users", {}, "call-1"))
# outcome.decision == "deny", with the typed reason; nothing executes.

Evidence chain:

from argus_sentry.evidence import SentryChainRecorder

chain = SentryChainRecorder(record_key=record_key, load_authority_key=load_key)
chain.start(policy_hash, policy_source=text)
# wire as the SentryCore recorder: every decision is signed into the chain
chain.export("gate_chain.json")
# then, offline: argus evidence verify gate_chain.json --level L2

Contents

License: proprietary. See the repository for the specification, the conformance matrix, and the verification walkthroughs.