Documentation

Everything you need to install the proxy, configure guardrails, and connect to estoppl cloud.

Getting Started

Install

# npm (recommended)
npm install -g estoppl

# Homebrew (macOS / Linux)
brew tap estoppl/tap && brew install estoppl

# Cargo (Rust)
cargo install estoppl

# Or try without installing
npx estoppl

Quick Start

# Initialize config and signing keys
estoppl init --agent-id my-agent

# Auto-wrap Claude Desktop or Cursor
estoppl wrap

# Restart your MCP client, then live-stream tool calls
estoppl tail

estoppl wrap discovers your MCP client configs and rewrites them to route tool calls through the proxy. The proxy runs as a subprocess — your MCP client starts it automatically. Restart your client after wrapping for changes to take effect.

Connect to estoppl Cloud

Sign up at app.estoppl.ai and grab your API key during onboarding. Then uncomment the [ledger] section in estoppl.toml:

[ledger]
cloud_api_key = "sk_your_key"
org_id = "your_org_id"

Cloud sync starts automatically. Events appear in your dashboard within seconds. The remote kill switch and human review also activate when org_id is set.

CLI Reference

Configuration

estoppl init generates estoppl.toml in the current directory:

[agent]
id = "my-agent"
version = "0.1.0"

[rules]
block_tools = ["delete_*", "drop_*"]
# human_review_tools = ["wire_transfer"]
# max_amount_usd = 50000.0
# rate_limit_per_minute = 30

# Connect to estoppl cloud (https://app.estoppl.ai)
[ledger]
# cloud_api_key = "sk_your_key"
# org_id = "your_org_id"

Guardrails

Cloud Sync

When cloud_api_key is set in estoppl.toml, the proxy automatically syncs events to the cloud. The endpoint defaults to https://api.estoppl.ai/v1/events.

Events always persist locally first. Cloud sync is best-effort with exponential backoff, gap detection, and automatic reconciliation.

When org_id is also set, two additional features activate:

• Remote kill switch — the proxy polls cloud policy every 5 seconds and hot-reloads rules
• Human review — HUMAN_REQUIRED decisions are submitted to the cloud for approval

Cloud API

Base URL: https://api.estoppl.ai. All requests require Authorization: Bearer <token>.

Dashboard API

These endpoints power the web dashboard at app.estoppl.ai. Auth: Clerk JWT or API key.

Policy Rules Reference

Custom Rules

Define arbitrary conditions on tool arguments:

{
  "custom_rules": [
    {
      "name": "Large transfers need approval",
      "tool": "wire_transfer",
      "condition": {"field": "amount", "operator": "gt", "value": 10000},
      "action": "human_review"
    }
  ]
}

Tool patterns: wire_transfer (exact), wire_* (prefix), * (all tools)

Operators: gt, lt, gte, lte, eq, neq, contains, not_contains

Actions: block, human_review, allow

Nested fields: Use dot notation — payment.total extracts from {"payment": {"total": 5000}}

Per-Agent Rules

Override org-wide rules for specific agents. Fields not specified fall back to org-wide defaults:

{
  "agent_rules": {
    "analytics-bot": {
      "allow_tools": ["read_*", "get_*"],
      "block_tools": ["wire_transfer"]
    }
  }
}

Field Redaction

Configure in estoppl.toml (proxy-side):

[rules]
redact_fields = ["ssn", "credit_card", "password"]

Redacted fields are replaced with [REDACTED] before syncing to the cloud.

Notifications

When a tool call requires human review, estoppl sends notifications to all configured channels with one-click approve/deny links:

• Slack — Block Kit message with Approve/Deny buttons
• Webhook — JSON payload with signed approve/deny URLs
• Email — HTML notification from alerts@estoppl.ai with one-click approve/deny

Configure via Settings in the dashboard or the notifications API endpoint.

Error Responses

All API errors return JSON: {"error": "description"}