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Your agents act. ACB decides what is allowed.

Agent Circuit Breaker is the deterministic guard layer between AI agents and real execution. It evaluates shell commands, SQL, files, packages, network calls, MCP tool arguments, and long-running action sequences before they run.

Install and test Open project hub
Action under review pre-execution gate
Live
Coding agent

Delete production cache directory

rm -rf /srv/production/cache
Risk High
Rule fs_recursive_delete
Coverage filesystem
Decision BLOCK
  • normalized shell input
  • matched destructive delete policy
  • returned auditable block result
Runtime Python 3.11+
Mode Local-first
Policy Deterministic

How it works

A control point before the tool call.

ACB receives the action an agent wants to take, inspects it with deterministic rules, and returns a typed decision before execution authority is granted.

01

Intercept

Capture proposed shell, SQL, filesystem, package, network, or MCP activity.

02

Evaluate

Apply built-in inspectors, custom rules, signed policy, and trajectory checks.

03

Decide

Return ALLOW, BLOCK, UNKNOWN, ERROR, or PENDING_APPROVAL with evidence.

Controls

Guard the paths where autonomous systems do real damage.

FS

Filesystem

Blocks recursive deletes, sensitive path changes, and dangerous permission shapes.

SQL

Database

Detects destructive statements, broad mutations, and risky unqualified operations.

NET

Network

Flags suspicious egress, metadata endpoint access, and secret-to-network patterns.

MCP

MCP tools

Checks stdio tool-call arguments and fails closed when forwarding is unknown.

PKG

Packages

Surfaces package install risk before an agent mutates the execution environment.

SEQ

Trajectories

Reviews action sequences for repeated blocks, scope drift, and staged escalation.

Agent Circuit Breaker deterministic safety pipeline diagram

Runtime posture

Clear decisions with evidence, not vague confidence.

Every decision is designed to be inspectable: what was normalized, which coverage ran, what rule matched, and why the final verdict was returned.

VerdictBLOCK
Reasondestructive filesystem operation
FallbackUNKNOWN stops by default

Project

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Try it locally

One install. One blocked action.

Start with the command line, then wire the same decision contract into Python, MCP, CI, or your agent runtime.

quickstart 
python -m pip install agent-circuit-breaker

agent-circuit-breaker check "rm -rf /"
# Verdict: BLOCK

agent-circuit-breaker check "mkdir /tmp/example"
# Verdict: ALLOW